Filed Pursuant to Rule 424(b)(5)
Under the Securities Act of 1933
Registration No. 333-213864

The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus do not constitute an offer to sell these securities and we are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to Completion, dated August 8, 2018

PROSPECTUS SUPPLEMENT

(To Prospectus dated September 29, 2016)

5,000,000 Shares

Common Stock

We expect to enter into forward sale agreements (collectively, the forward sale agreements) with an affiliate of Barclays Capital Inc. and an affiliate of Citigroup Global Markets Inc., which affiliates we refer to in such capacity as the “forward purchasers,” with respect to 5,000,000 shares of our common stock. In connection with these forward sale agreements, the forward purchasers or their respective affiliates, whom we refer to in such capacity as the “forward sellers,” at our request, are borrowing from third parties and selling to the underwriters an aggregate of 5,000,000 shares of our common stock.

We will not receive any proceeds from the sale of our common stock by the forward sellers to the underwriters. We currently expect to fully physically settle the forward sale agreements and receive cash proceeds, subject to certain adjustments pursuant to the forward sale agreements, upon one or more settlement dates on or prior to August 1, 2019, which is the final settlement date under the forward sale agreements. If we elect to cash settle all or a portion of the forward sale agreements, we may not receive any proceeds from such election, and we may owe cash to the forward purchasers. If we elect to net share settle all or a portion of the forward sale agreements, we will not receive any cash proceeds from such election, and we may owe shares of our common stock to the forward purchasers. See “Underwriting (Conflicts of Interest)—Forward Sale Agreements.”

A forward seller is not required to borrow shares if, after using commercially reasonable efforts, it is unable to borrow such shares, or if borrowing costs exceed a specified threshold or if certain conditions specified in the underwriting agreement have not been satisfied. If any forward seller does not deliver and sell all of the shares of our common stock to be sold by it, we will issue and sell to the underwriters a number of shares of our common stock equal to the number of shares that such forward seller does not deliver and sell, and the number of shares underlying the relevant forward sale agreement will be decreased by the number of shares that we issue and sell.

Our common stock is listed on the New York Stock Exchange, or NYSE, under the symbol “KRC.” The last reported sale price of our common stock on the NYSE on August 7, 2018 was $73.57 per share.

Shares of our common stock are subject to certain restrictions on ownership and transfer designed to preserve our qualification as a real estate investment trust for federal income tax purposes. See “Description of Capital Stock—Restrictions on Ownership and Transfer of the Company’s Capital Stock” in the accompanying prospectus.

An investment in our common stock involves various risks and prospective investors should carefully consider the matters discussed under “Risk Factors” beginning on page S-8 of this prospectus supplement and the matters discussed in the documents incorporated by reference in this prospectus supplement and the accompanying prospectus before making a decision to invest in our common stock.

The forward sellers have granted the underwriters an option to purchase a maximum of 750,000 additional shares of our common stock exercisable in whole or in part at any time and from time to time through and including the 30th day after the date of this prospectus supplement. Upon any exercise of such option, the total number of shares of our common stock underlying each forward sale agreement will be increased by the number of shares sold by the applicable forward seller in respect of such option exercise. A forward seller is not required to borrow shares for delivery upon exercise of such option by the underwriters if, after using commercially reasonable efforts, it is unable to borrow such shares, or if borrowing costs exceed a specified threshold or if certain conditions specified in the underwriting agreement have not been satisfied. If any forward seller does not deliver and sell all of the shares of our common stock to be sold by it in connection with the exercise of such option, we will issue and sell to the underwriters a number of shares of our common stock equal to the number of shares that such forward seller does not deliver and sell, and the number of shares underlying the relevant forward sale agreement will not be increased in respect of the number of shares that we issue and sell.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

We expect that the shares of common stock will be ready for delivery through The Depository Trust Company on or about                 , 2018.

Joint-Book Running Managers

Prospectus Supplement dated                     , 2018

TABLE OF CONTENTS

Prospectus Supplement

Prospectus

S-i

Kilroy Realty Corporation, or the Company, is the sole general partner of Kilroy Realty, L. P., or the operating partnership. Unless otherwise expressly stated or the context otherwise requires, in this prospectus supplement and the accompanying prospectus, “we,” “us” and “our” refer collectively to the Company, the operating partnership and the Company’s other subsidiaries. References in this prospectus supplement to the operating partnership’s revolving credit facility mean the operating partnership’s $750 million unsecured revolving credit facility, and references in this prospectus supplement to the operating partnership’s term loan facility mean the operating partnership’s $150 million unsecured term loan facility, unless otherwise expressly stated or the context otherwise requires, in each case as amended or supplemented from time to time.

You should rely only on the information contained in this prospectus supplement and the accompanying prospectus, the documents incorporated or deemed to be incorporated by reference herein or therein and any free writing prospectus that we may prepare in connection with this offering. We have not, and the underwriters, the forward sellers and the forward purchasers have not, authorized anyone to provide you with any information or make any representation that is different. If anyone provides you with any additional or different information, you should not rely on it. Neither this prospectus supplement nor the accompanying prospectus nor any such free writing prospectus is an offer to sell or a solicitation of an offer to buy any securities other than the common stock to which this prospectus supplement relates or an offer to sell or the solicitation of an offer to buy securities in any jurisdiction where, or to any person to whom, it is unlawful to make an offer or solicitation. You should not assume that the information contained in this prospectus supplement, the accompanying prospectus, any document incorporated or deemed to be incorporated by reference herein or therein or any free writing prospectus that we may provide you in connection with this offering is accurate on any date after the respective dates of those documents. Our business, financial condition, liquidity, results of operations, funds from operations and prospects may have changed since those respective dates.

Industry and Market Data

In this prospectus supplement and the documents incorporated and deemed to be incorporated by reference in this prospectus supplement and the accompanying prospectus, we refer to information and statistics regarding, among other things, the industry, markets, submarkets and sectors in which we operate, including, among other things, whether and, if applicable, the percentage by which certain leases are above or below applicable market rents, estimated completion dates and costs of properties under development, and the number of square feet of office and other space that could be developed from specific parcels of undeveloped land, which we refer to as “density.” We obtained this information and these statistics from various third-party sources and our own internal estimates. We believe that these sources and estimates are reliable, but this information and these statistics (whether obtained from third-party sources or based on our internal estimates) are subject to assumptions, estimates and other uncertainties, and we have not independently verified them and cannot guarantee their accuracy or completeness.

S-ii

S-1

S-2

S-3

S-4

S-5

S-6

S-7

RISK FACTORS

Investing in our common stock involves risks. Before acquiring any common stock pursuant to this prospectus supplement and the accompanying prospectus, you should carefully consider the information contained in this prospectus supplement, the accompanying prospectus, the documents incorporated or deemed to be incorporated by reference herein or therein and any free writing prospectus that we may prepare in connection with this offering, including, without limitation, the risks set forth below and under the captions “Item 1A. Risk Factors” and “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our and the operating partnership’s Annual Report on Form 10-K for the year ended December 31, 2017 filed with the SEC, under the captions “Item 1A. Risk Factors” and “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our and the operating partnership’s Quarterly Reports on Form 10-Q for the quarters ended March 31, 2018 and June 30, 2018 filed with the SEC and as described in our other filings with the SEC. The occurrence of any of these risks could materially and adversely affect our business, financial condition, liquidity, results of operations, funds from operations and prospects, as well as the trading price of our common stock, and might cause you to lose all or a part of your investment in our common stock. Please also refer to the sections “Industry and Market Data” and “Forward-Looking Statements” in this prospectus supplement.

Risks Related to Our Business and Operations

The actual density of our undeveloped land holdings and/or any particular land parcel may not be consistent with our potential density estimates.

As of June 30, 2018, we estimate that our seven potential development sites, representing approximately 80 gross acres of undeveloped land, provide from 5.5 million to 6.5 million square feet of potential rentable office or other space, which we refer to as “density.” We caution you not to place undue reliance on the potential density estimates for our undeveloped land holdings and/or any particular land parcel because they are based solely on our estimates, using data currently available to us, and our business plans as of June 30, 2018. The actual density of our undeveloped land holdings and/or any particular land parcel may differ substantially from our estimates based on numerous factors, including our inability to obtain necessary zoning, land use and other required entitlements, as well as building, occupancy and other required governmental permits and authorizations, and changes in the entitlement, permitting and authorization processes that may restrict or delay our ability to develop, redevelop or use undeveloped land holdings at anticipated density levels, or at all. Moreover, we may strategically choose not to develop, redevelop or use our undeveloped land holdings to their maximum potential density or be unable to do so as a result of factors beyond our control, including our inability to obtain capital on terms that are acceptable to us, or at all, to fund our development and redevelopment activities. We can provide no assurance that the actual density of our undeveloped land holdings and/or any particular land parcel will be consistent with our potential density estimates.

The trading price of our common stock may fluctuate significantly.

The trading price of our common stock may fluctuate significantly. From January 1, 2018 through August 7, 2018, the closing sale price of Company’s common stock on the New York Stock Exchange, or the NYSE, ranged from $63.72 to $77.34 per share. The trading price of our common stock may fluctuate in response to many factors, including:

S-8

Many of the factors listed above are beyond our control. These factors may cause the trading price of our common stock to decline, regardless of our financial performance and condition and prospects. It is impossible to provide any assurance that the trading price of our common stock or the amount of dividends we pay on our common stock will not decline in the future, and it may be difficult for holders to resell shares of our common stock at prices they find attractive or at all.

Risks Related to the Forward Sale Agreements

The physical settlement of the forward sale agreements and future issuances of our common stock could be dilutive to our earnings per share and funds from operations per share.

Giving effect to the issuance and sale by us of any shares of our common stock upon the physical settlement of the forward sale agreements, the receipt of the expected net proceeds therefrom and the use of those net proceeds, the physical settlement of the forward sale agreements could have a dilutive effect on our earnings per share and funds from operations per share. In addition, to the extent we elect net share settlement under the forward sale agreements, any shares of common stock we issue to the forward purchasers in connection therewith could also have a dilutive effect on our earnings per share and funds from operations per share. Likewise, to the extent we issue and sell any shares to the underwriters in connection with this offering in lieu of shares that would otherwise been sold to the underwriters by the forward sellers, the issuance and sale of those shares may have a similar dilutive impact. Additional issuances of our common stock including in connection with development activity and acquisitions, if any, could also be dilutive to our earnings per share and funds from operations per share. The issuance or sale by us of our common stock (including in connection with the physical settlement or net share settlement of the forward sale agreements, in lieu of shares that would otherwise been sold to the underwriters by the forward sellers, in connection with development activities or acquisitions, upon

S-9

redemption of the operating partnership’s common units, upon the issuance of shares of common stock under our stock option and other equity incentive plans or pursuant to options or other awards granted under those plans, or pursuant to our at-the-market common stock offering program), or the perception that such additional issuances or sales could occur, could also adversely affect our earnings per share and funds from operations per share, the trading price of our common stock and our ability to raise capital through future offerings of equity or equity-related securities. In addition, if we are unable to apply the net proceeds we may receive from the physical settlement of the forward sale agreements or from any shares we may issue to the underwriters in lieu of shares that would otherwise have been sold to the underwriters by the forward sellers, or from the issuance and sale of our common stock under other circumstances, to make investments in properties that generate sufficient revenues to offset the dilutive impact of the issuance of shares of our common stock, there will be further dilution of our earnings per share and funds from operations per share. Funds from operations is not a financial metric under generally accepted accounting principles, or GAAP. For a reconciliation of our funds from operations to the nearest comparable GAAP financial metric and for additional information on how we compute funds from operations, see “Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Non-GAAP Supplemental Financial Measure: Funds From Operations” in our and the operating partnership’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2018, which is incorporated by reference in this prospectus supplement and the accompanying prospectus.

Settlement provisions contained in any forward sale agreement subject us to certain risks.

Each forward purchaser will have the right to accelerate the settlement of all or any portion of the shares underlying its forward sale agreement (except with respect to events specified in (1) and (3) below, where accelerated settlement is limited to the portion of shares whose settlement would address the relevant event or that is affected by the relevant event) that it enters into with us and to require us to physically settle such shares on a date specified by such forward purchaser if: (1) in such forward purchaser’s commercially reasonable judgment, it or its affiliate is unable to hedge (or maintain a hedge of) its exposure in a commercially reasonable manner under such forward sale agreement because (x) insufficient shares of our common stock have been made available for borrowing by securities lenders or (y) such forward purchaser or any of its affiliates would incur a stock borrow cost in excess of a specified threshold; (2) we declare any distribution, issue or dividend on shares of our common stock (a) payable in cash in excess of specified amounts, (b) that constitutes an extraordinary dividend under such forward sale agreement, (c) payable in securities of another company as a result of a spin-off or similar transaction, or (d) payable in any other type of securities (other than our common stock), rights, warrants or other assets for payment at less than the prevailing market price; (3) certain ownership thresholds applicable to such forward purchaser and its affiliates are or would be exceeded; (4) an event is announced that if consummated would result in a specified extraordinary event (including certain mergers or tender offers, as well as certain events involving our nationalization, our insolvency, a delisting of our common stock or change in law); or (5) certain other events of default or termination events occur, including, among others, any material misrepresentation made by us in connection with such forward sale agreement or our insolvency (each as more fully described in the relevant forward sale agreement).

A forward purchaser’s decision to exercise its right to accelerate all or a portion of the settlement of its forward sale agreement and to require us to physically settle the relevant shares will be made irrespective of our interests, including our need for capital. In such cases, we could be required to issue and deliver shares of our common stock under the terms of the physical settlement provisions of the applicable forward sale agreement irrespective of our capital needs, which would result in dilution to our earnings per share and funds from operations per share. In addition, we would be obligated to issue some or all of the shares offered hereby pursuant to the underwriting agreement in the event that the number of shares underlying the forward sale agreements is reduced or eliminated, as described in “Underwriting (Conflicts of Interest)–Forward Sale Agreements.”

Each of the forward sale agreements provides that the forward sale price will be subject to adjustment on a daily basis based on a floating interest rate factor equal to a specified daily rate less a spread and will be

S-10

decreased by amounts related to expected quarterly dividends on our common stock during the term of such forward sale agreement. If the specified daily rate is less than the spread on any day, the interest rate factor will result in a daily reduction of the forward sale price.

Except under certain circumstances, we also have the right to elect cash settlement or net share settlement under the forward sale agreements. If we elect to cash or net share settle all or any part of a forward sale agreement with a forward purchaser, we would expect the relevant forward purchaser or its affiliates to purchase shares of our common stock in secondary market transactions over an unwind period to:

If the price of our common stock at which these purchases by such forward purchaser (or its affiliate) are made is below the relevant forward price, such forward purchaser will pay us the difference in cash (if we elect to cash settle) or deliver to us shares of our common stock having a market value equal to such difference (if we elect to net share settle). If the price of our common stock at which these purchases are made by such forward purchaser (or its affiliate) exceeds the applicable forward price, we will pay such forward purchaser an amount in cash equal to such difference (if we elect to cash settle) or we will deliver to such forward purchaser a number of shares of our common stock having a market value equal to such difference (if we elect to net share settle). Any such difference could be significant and could result in our receipt of a significant amount of cash or number of shares of our common stock from such forward purchaser or require us to pay a significant amount of cash or deliver a significant number of shares of our common stock to such forward purchaser. See “Underwriting (Conflicts of Interest)—Forward Sale Agreements.”

In addition, the purchase of our common stock by a forward purchaser or its affiliate to unwind the forward purchaser’s hedge position could cause the price of our common stock to increase above the price that would have prevailed in the absence of those purchases (or prevent or lessen a decrease in such price), thereby increasing the amount of cash (in the case of cash settlement) or the number of shares (in the case of net share settlement) that we would owe to such forward purchaser upon settlement of the applicable forward sale agreement or decrease the amount of cash (in the case of cash settlement) or the number of shares (in the case of net share settlement) that such forward purchaser would owe us upon settlement of the applicable forward sale agreement.

In case of our bankruptcy or insolvency, the forward sale agreements that are then in effect will automatically terminate, and we would not receive the expected net proceeds from forward sales of shares of our common stock.

If we file for or consent to a proceeding seeking a judgment in bankruptcy or insolvency or any other relief under any bankruptcy or insolvency law or other similar law affecting creditors’ rights, or we or a regulatory authority with jurisdiction over us presents a petition for our winding-up or liquidation, or we consent to such a petition, the forward sale agreements that are then in effect will automatically terminate. If any such forward sale agreement so terminates under these circumstances, we would not be obligated to deliver to the relevant forward purchaser any shares of our common stock not previously delivered, and the relevant forward purchaser would be discharged from its obligations to pay the forward price per share in respect of any shares of our common stock not previously settled under the applicable forward sale agreement. Therefore, to the extent that there are any shares of our common stock with respect to which a forward sale agreement has not been settled at the time of the commencement of any such bankruptcy or insolvency proceedings, we would not receive the relevant forward price per share in respect of those shares of our common stock.

S-11

FORWARD-LOOKING STATEMENTS

This prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein or therein, contain, and documents we subsequently file with the SEC and incorporate by reference herein or therein may contain, certain “forward-looking statements” within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, including, among other things, statements or information concerning our plans, objectives, capital resources, portfolio performance, results of operations, projected future occupancy and rental rates, lease expirations, debt maturities, potential investments, strategies such as capital recycling, development and redevelopment activity, projected construction costs, projected construction commencement and completion dates, projected square footage of space that could be constructed on undeveloped land that we own, projected rentable square footage of or number of units in properties under construction or in the development pipeline, anticipated proceeds from capital recycling activity or other dispositions and anticipated dates of those activities or dispositions, projected increases in the value of properties, dispositions, future executive incentive compensation, pending, potential or proposed acquisitions, the anticipated use of proceeds we receive from this offering or from the settlement under the forward sale agreements, plans to grow our net operating income and funds from operations, our ability to re-lease properties at or above current market rates, anticipated market conditions and demographics and other forward-looking financial data. Forward-looking statements can be identified by the use of words such as “believes,” “expects,” “projects,” “may,” “will,” “should,” “seeks,” “approximately,” “intends,” “plans,” “pro forma,” “estimates” or “anticipates” and the negative of these words and phrases and similar expressions that do not relate to historical matters. Forward-looking statements are based on our current expectations, beliefs and assumptions, and are not guarantees of future performance. Forward-looking statements are inherently subject to uncertainties, risks, changes in circumstances, trends and factors that are difficult to predict, many of which are outside of our control. Accordingly, actual performance, results and events may vary materially from those indicated in the forward-looking statements, and you should not rely on the forward-looking statements as predictions of future performance, results or events. Numerous factors could cause actual future performance, results and events to differ materially from those indicated in the forward-looking statements, including, among others:

S-12

The risk factors included in this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein or therein, and documents we subsequently file with the SEC and incorporate by reference herein or therein, are not exhaustive and additional factors could adversely affect our business and financial performance. For a discussion of additional factors that could materially adversely affect the Company’s business and financial performance, see the factors included under the caption “Risk Factors” in this prospectus supplement and in the accompanying prospectus, in Kilroy Realty Corporation’s and Kilroy Realty, L.P.’s Annual Report on Form 10-K for the year ended December 31, 2017, as well as the other risks described in this prospectus supplement and the accompanying prospectus and the documents incorporated by reference herein or therein or in any free writing prospectus we may provide you with in this offering. All forward-looking statements are based on information that was available and speak only as of the dates on which they were made. We assume no obligation to update any forward-looking statement that becomes untrue because of subsequent events, new information or otherwise, except to the extent we are required to do so in connection with our ongoing requirements under federal securities laws.

S-13

USE OF PROCEEDS

We will not receive any proceeds from the sale of shares of our common stock by the forward sellers in this offering unless an event occurs that requires us to sell shares to the underwriters in lieu of the forward sellers selling such shares. We currently expect to fully physically settle the forward sale agreements (by the delivery and sale of shares of our common stock to the forward purchasers) and receive cash proceeds, subject to certain adjustments pursuant to the forward sale agreements, upon one or more settlement dates on or prior to August 1, 2019, which is the final settlement date under the forward sale agreements, selected by us. Except in certain circumstances, we also have the right to elect cash settlement or net share settlement under the forward sale agreements. If we elect to cash settle all or a portion of our obligations under a forward sale agreement, we would expect to receive an amount of net cash proceeds that is significantly lower than the amount we would have received upon physical settlement, and we may not receive any net proceeds (or we may owe cash, which could be a significant amount, to the applicable forward purchaser). If we elect to net share settle all or a portion of our obligations under a forward sale agreement, we would not receive any cash proceeds from the applicable forward purchaser (or we may be required to deliver shares of our common stock to such forward purchaser, and the amount of those shares could be significant). The forward sale agreements are also subject to acceleration by the forward purchasers upon the occurrence of certain events. See “Underwriting (Conflicts of Interest)—Forward Sale Agreements.”

Assuming full physical settlement of the forward sale agreements at an initial forward sale price of $        per share (which is equal to the public offering price per share less the underwriting discounts and commissions per share as set forth on the cover page of this prospectus supplement), we would expect to receive net proceeds of approximately $         million, or approximately $         million if the underwriters exercise their option to purchase additional shares in full, in each case after deducting discounts and commissions and estimated expenses payable by us related to the forward sale agreements and this offering), subject to certain adjustments pursuant to the forward sale agreements. Each of the forward sale agreements provides that the forward sale price will be subject to adjustment on a daily basis based on a floating interest rate factor equal to a specified daily rate less a spread and will be decreased by amounts related to expected quarterly dividends on our common stock during the term of such forward sale agreement. If the specified daily rate is less than the spread on any day, the interest rate factor will result in a daily reduction of the forward sale price. As of the date of this prospectus supplement, the specified daily rate was greater than the spread, but we can give no assurance that this rate will not decrease to a rate below the spread during the term of the forward sale agreements.

We intend to use the net proceeds, if any, received upon the settlement of the forward sale agreements (and from the sale of any shares of common stock sold by us to the underwriters in lieu of shares that would otherwise have been sold to the underwriters by the forward sellers) for general corporate purposes, which may include funding development projects, acquiring land and properties and repaying outstanding indebtedness, which may include borrowings, if any, under the operating partnership’s revolving credit facility and term loan facility. Pending application of the net proceeds for these purposes, we may temporarily invest such net proceeds in marketable securities. As of August 6, 2018, we had borrowings of $320.0 million outstanding under the operating partnership’s unsecured revolving credit facility and borrowings of $150.0 million outstanding under its unsecured term loan facility. The unsecured revolving credit facility matures in July 2022 and, as of August 6, 2018, bore interest at a rate equal to the London Interbank Offered Rate, or LIBOR, plus 1.00%, and the unsecured term loan facility matures in July 2022 and, as of August 6, 2018, bore interest at a rate equal to LIBOR plus 1.10%. Proceeds from borrowings under the unsecured revolving credit facility and unsecured term loan facility were applied for general corporate purposes, including funding development and redevelopment projects, acquiring land and properties and repaying other indebtedness. Any borrowings under any revolving credit facility that are repaid with any such net proceeds may be reborrowed, subject to customary conditions.

All of the proceeds from the sale of shares of our common stock offered by the forward sellers in this offering (excluding proceeds, if any, we may receive from the sale of shares of common stock to the underwriters

S-14

in lieu of shares of common stock that would otherwise have been sold by the forward sellers) will be paid to the forward sellers. Because Barclays Capital Inc. and Citigroup Global Markets Inc., or their affiliates, as applicable, in their capacity as forward sellers, will receive more than 5% of the proceeds of this offering, Barclays Capital Inc. and Citigroup Global Markets Inc. are deemed to have a conflict of interest. However, because REITs are not subject to Rule 5121 of the Financial Industry Regulatory Authority, Inc., or FINRA, regarding conflicts of interest, the appointment of a “qualified independent underwriter” is not required in connection with this offering.

In addition, as described above, any net proceeds we may receive from the sale of any shares of common stock, if any, that we may sell the underwriters in lieu of shares that would otherwise have been sold by the forward sellers may be used to repay outstanding indebtedness. Affiliates of the underwriters participating in this offering are lenders under the operating partnership’s revolving credit facility and term loan facility, and the underwriters and/or their respective affiliates may from time to time hold debt securities or other indebtedness of ours or any of our subsidiaries. To the extent that we use any such net proceeds to repay any of our outstanding indebtedness (including bank loans) held by any of the underwriters or their affiliates, they will receive proceeds from this offering through the repayment of that indebtedness. If 5% or more of such net proceeds (not including the underwriting discount) is used to repay indebtedness owed to at least one of the underwriters and/or affiliates of such underwriter, such underwriter or underwriters will also be deemed to have a conflict of interest. However, because REITs are not subject to FINRA Rule 5121 regarding conflicts of interest, the appointment of a “qualified independent underwriter” is not required in connection with this offering. For additional information, see “Underwriting (Conflicts of Interest)—Conflicts of Interest” and “Underwriting (Conflicts of Interest)—Other Relationships” in this prospectus supplement.

S-15

SUPPLEMENTAL UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS

For a discussion of certain material United States federal income tax considerations regarding the Company and an investment in the common stock offered hereby, please see Exhibit 99.1 to our and the operating partnership’s Current Report on Form 8-K filed with the SEC on February 13, 2018 (the “February 13 Form 8-K”), which was filed pursuant to Item 8.01 of Form 8-K. The February 13 Form 8-K (including Exhibit 99.1 thereto) is incorporated by reference in this prospectus supplement and the accompanying prospectus and supersedes and replaces, in their entirety, (i) the discussion under the heading “United States Federal Income Tax Considerations” in the accompanying prospectus and the related registration statement on Form S-3 (File Nos. 333-213864 and 333-213864-01) filed by us and the operating partnership with the SEC on September 29, 2016, and (ii) the discussion set forth in Exhibit 99.1 to our and the operating partnership’s Current Report on Form 8-K filed with the SEC on October 30, 2017, which was filed with respect to Item 8.01 of Form 8-K. The February 13 Form 8-K may be obtained as described under “Where You Can Find More Information” in the accompanying prospectus. See “Incorporation of Certain Documents By Reference.” Prospective investors in the common stock offered hereby should consult their tax advisors regarding the United States federal income and other tax considerations to them of the acquisition, ownership and disposition of the common stock offered by this prospectus supplement and the accompanying prospectus. Prospective investors should also carefully review the discussion appearing in Exhibit 99.1 to the February 13 Form 8-K, as well as the other information included and incorporated by reference in this prospectus supplement and the accompanying prospectus, before acquiring any of the shares of common stock offered by this prospectus supplement and the accompanying prospectus.

S-16

SUPPLEMENTAL DESCRIPTION OF CAPITAL STOCK

The information appearing in the accompanying prospectus under the captions “Description of Capital Stock” and “Certain Provisions of Maryland Law and of the Company’s Charter and Bylaws” has been supplemented and a portion of such information has been superseded by the information appearing in the Company’s Current Reports on Form 8-K (including the exhibits thereto) filed with the SEC on February 1, 2017 and August 23, 2017, which are incorporated by reference in this prospectus supplement and the accompanying prospectus and which may be obtained as described under “Where You Can Find More Information” in the accompanying prospectus. See “Incorporation of Certain Documents By Reference.” Prospective investors should carefully review the information in those Current Reports, as well as the other information included and incorporated by reference in this prospectus supplement and the accompanying prospectus, before acquiring any of the shares of common stock offered by this prospectus supplement and the accompanying prospectus.

S-17

UNDERWRITING (CONFLICTS OF INTEREST)

The shares of common stock will be offered through the underwriters named below. Barclays Capital Inc. and Citigroup Global Markets Inc. are acting as representatives (the “representatives”) of the underwriters. Subject to the terms and conditions described in an underwriting agreement among us, the operating partnership, the forward sellers and the representatives of the underwriters, the forward sellers have agreed to sell to the underwriters, and the underwriters severally have agreed to purchase from the forward sellers, the respective number of shares listed opposite the underwriters’ names below.

The underwriters have agreed to purchase all of the shares sold under the underwriting agreement if any of these shares are purchased. If an underwriter defaults, the underwriting agreement provides that the purchase commitments of the non-defaulting underwriter may be increased or the underwriting agreement may be terminated.

We and the operating partnership have agreed to indemnify the underwriters, the forward sellers and the forward purchasers against certain liabilities, including liabilities under the Securities Act of 1933, as amended, or to contribute to payments the underwriters, the forward sellers and the forward purchasers may be required to make in respect of those liabilities.

The underwriters are offering the shares, subject to prior sale, when, as and if delivered to and accepted by them, subject to approval of legal matters by their counsel and other conditions contained in the underwriting agreement, such as the receipt by the underwriters of officers’ certificates. The underwriters reserve the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

Forward Sale Agreements

We expect to enter into forward sale agreements on the date of this prospectus supplement with the forward purchasers relating to an aggregate of 5,000,000 shares of our common stock. In connection with the execution of the forward sale agreements, and at our request, the forward sellers are borrowing from third parties and selling in this offering 5,000,000 shares of our common stock.

A forward seller is not required to borrow shares if, after using commercially reasonable efforts, it is unable to borrow such shares, or if borrowing costs exceed a specified threshold or if certain conditions specified in the underwriting agreement have not been satisfied. If any forward seller does not deliver and sell all of the shares of our common stock to be sold by it pursuant to the terms of the underwriting agreement, we will issue and sell directly to the underwriters a number of shares of our common stock equal to the number of shares that such forward seller does not deliver and sell, and, under such circumstances, the number of shares of our common stock underlying the relevant forward sale agreement will be decreased by the number of shares of our common stock that we issue and sell. Under any such circumstance, the commitment of the underwriters to purchase shares of our common stock from the relevant forward seller, as described above, will be replaced with the commitment to purchase from us, at the same price at which the underwriters have agreed to purchase the shares of our common stock from such forward seller, the relevant number of shares of our common stock not sold by such forward seller.

We will not receive any proceeds from the sale of shares of our common stock by the forward sellers in this offering unless an event occurs that requires us to sell shares to the underwriters in lieu of the forward sellers

S-18

selling such shares. We currently expect to fully physically settle the forward sale agreements and receive cash proceeds, subject to certain adjustments pursuant to the forward sale agreements, upon one or more settlement dates on or prior to August 1, 2019, which is the final settlement date under the forward sale agreements, selected by us. Although we expect to settle the forward sale agreements entirely by the delivery of shares of our common stock upon physical settlement, we may elect, subject to certain conditions, cash settlement or net share settlement for all or a portion of our obligations under the forward sale agreements. For example, we may conclude that it is in our interest to cash settle or net share settle the forward sale agreements if we have no current use for all or a portion of the net proceeds due upon physical settlement of the forward sale agreements.

On a settlement date or dates, if we decide to physically settle the forward sale agreements, we will issue shares of our common stock to the forward purchasers at the then-applicable forward sale price. The forward sale price will initially be $         per share. Each of the forward sale agreements provides that the forward sale price will be subject to adjustment on a daily basis based on a floating interest rate factor equal to a specified daily rate less a spread and will be decreased by amounts related to expected quarterly dividends on our common stock during the term of such forward sale agreement. If the specified daily rate is less than the spread on any day, the interest rate factor will result in a daily reduction of the forward sale price. As of the date of this prospectus supplement, the specified daily rate was greater than the spread, but we can give no assurance that this rate will not decrease to a rate below the spread during the term of the forward sale agreements.

Except in certain circumstances, we have the right to elect cash settlement or net share settlement under the forward sale agreements. If we elect to cash settle all or a portion of our obligations under a forward sale agreement, we would expect to receive an amount of net cash proceeds that is significantly lower than the amount we would have received upon physical settlement, and we may not receive any net proceeds (or we may owe cash, which could be a significant amount, to the applicable forward purchaser). If we elect to net share settle all or any portion of our obligations under a forward sale agreement, we would not receive any cash proceeds from the applicable forward purchaser (or we may be required to deliver shares of our common stock to such forward purchaser, and the amount of those shares could be significant).

If we elect to cash or net share settle all or any part of a forward sale agreement with a forward purchaser, we would expect the relevant forward purchaser or its affiliates to purchase shares of our common stock in secondary market transactions over an unwind period to:

If the price of our common stock at which these purchases by such forward purchaser (or its affiliate) are made is below the relevant forward price, such forward purchaser will pay us the difference in cash (if we elect to cash settle) or deliver to us shares of our common stock having a market value equal to such difference (if we elect to net share settle). If the price of our common stock at which these purchases are made by such forward purchaser (or its affiliate) exceeds the applicable forward price, we will pay such forward purchaser an amount in cash equal to such difference (if we elect to cash settle) or we will deliver to such forward purchaser a number of shares of our common stock having a market value equal to such difference (if we elect to net share settle). Any such difference could be significant and could result in our receipt of a significant amount of cash or number of shares of our common stock from such forward purchaser or require us to pay a significant amount of cash or deliver a significant number of shares of our common stock to such forward purchaser.

In addition, the purchase of our common stock by a forward purchaser or its affiliate to unwind the forward purchaser’s hedge position could cause the price of our common stock to increase above the price that would

S-19

have prevailed in the absence of those purchases (or prevent or lessen a decrease in such price), thereby increasing the amount of cash (in the case of cash settlement) or the number of shares (in the case of net share settlement) that we would owe to such forward purchaser upon settlement of the applicable forward sale agreement or decrease the amount of cash (in the case of cash settlement) or the number of shares (in the case of net share settlement) that such forward purchaser would owe us upon settlement of the applicable forward sale agreement.

Before the issuance of shares of our common stock, if any, upon settlement of the forward sale agreements, we expect that the shares issuable upon settlement of the forward sale agreements will be reflected in our earnings per share calculation using the treasury stock method. Under this method, the number of shares of our common stock used in calculating earnings per share is deemed to be increased by the excess, if any, of the number of shares of common stock that would be issued upon full physical settlement of the forward sale agreements over the number of shares of common stock that could be purchased by us in the market (based on the average market price of our common stock during the applicable reporting period) using the proceeds receivable upon full physical settlement (based on the adjusted forward sale price at the end of the reporting period). Consequently, we anticipate there will be no dilutive effect on our earnings per share except during periods when the average market price of shares of our common stock is above the applicable adjusted forward sale price, which is initially $         per share, subject to adjustment on a daily basis based on a floating interest rate factor equal to a specified daily rate less a spread and subject to decrease by amounts related to expected quarterly dividends on our common stock during the term of the forward sale agreements. However, if we decide to physically settle or, to the extent we are obligated to deliver shares of our common stock, net share settle the forward sale agreements, delivery of our shares to the forward purchasers on any such physical settlement or net share settlement of the forward sale agreements would result in dilution to our earnings per share.

Each forward purchaser will have the right to accelerate the settlement of all or any portion of the shares underlying its forward sale agreement (except with respect to events specified in (1) and (3) below, where accelerated settlement is limited to the portion of shares whose settlement would address the relevant event or that is affected by the relevant event) that it enters into with us and to require us to physically settle such shares on a date specified by such forward purchaser if: (1) in such forward purchaser’s commercially reasonable judgment, it or its affiliate is unable to hedge (or maintain a hedge of) its exposure in a commercially reasonable manner under such forward sale agreement because (x) insufficient shares of our common stock have been made available for borrowing by securities lenders or (y) such forward purchaser or any of its affiliates would incur a stock borrow cost in excess of a specified threshold; (2) we declare any distribution, issue or dividend on shares of our common stock (a) payable in cash in excess of specified amounts, (b) that constitutes an extraordinary dividend under such forward sale agreement, (c) payable in securities of another company as a result of a spin-off or similar transaction, or (d) payable in any other type of securities (other than our common stock), rights, warrants or other assets for payment at less than the prevailing market price; (3) certain ownership thresholds applicable to such forward purchaser and its affiliates are or would be exceeded; (4) an event is announced that if consummated would result in a specified extraordinary event (including certain mergers or tender offers, as well as certain events involving our nationalization, our insolvency, a delisting of our common stock or change in law); or (5) certain other events of default or termination events occur, including, among others, any material misrepresentation made by us in connection with such forward sale agreement or our insolvency (each as more fully described in the relevant forward sale agreement).

A forward purchaser’s decision to exercise its right to accelerate all or a portion of the settlement of its forward sale agreement and to require us to physically settle the relevant shares will be made irrespective of our interests, including our need for capital. In such cases, we could be required to issue and deliver shares of our common stock under the terms of the physical settlement provisions of the applicable forward sale agreement irrespective of our capital needs, which could result in dilution to our earnings per share and funds from operations per share. In addition, we would be obligated to issue some or all of the shares offered hereby pursuant to the underwriting agreement in the event that the number of shares underlying the forward sale agreements is reduced or eliminated.

S-20

The foregoing is a description of certain provisions of the forward sale agreements we expect to enter into in connection with this offering. The descriptions of certain provisions of the forward sale agreements appearing above and elsewhere in this prospectus supplement are not complete and are subject to, and qualified in their entirety by reference to, the terms and provisions of such forward sale agreements. A form of the forward sale agreement is available upon request from us at the address set forth in the section of the accompanying prospectus entitled “Where You Can Find More Information.”

Commissions and Discounts

The representatives have advised us that the underwriters propose initially to offer the shares to the public at the public offering price appearing on the cover page of this prospectus supplement and to dealers at that price less a concession not in excess of $         per share. After the public offering, the public offering price and concession may be changed.

The following table shows the public offering price and underwriting discounts and commissions. The information assumes either no exercise or full exercise by the underwriters of their option to purchase additional shares.

The expenses of this offering, not including the underwriting discounts and commissions, are estimated at $425,000 and are payable by us.

Option to Purchase Additional Shares

The forward sellers have granted the underwriters an option to purchase up to 750,000 additional shares of our common stock exercisable in whole or in part at any time and from time to time through and including the 30th day after the date of this prospectus supplement. Upon any exercise of such option, the total number of shares of our common stock underlying each forward sale agreement will be increased by the number of shares sold by the applicable forward seller in respect of such option exercise. A forward seller is not required to borrow shares for delivery upon exercise of such option by the underwriters if, after using commercially reasonable efforts, it is unable to borrow such shares, or if borrowing costs exceed a specified threshold or certain conditions specified in the underwriting agreement have not been satisfied. If any forward seller does not deliver and sell all of the shares of our common stock to be sold by it in connection with the exercise of such option, we will issue and sell to the underwriters a number of shares of our common stock equal to the number of shares that such forward seller does not deliver and sell, and the number of shares underlying the relevant forward sale agreement will not be increased in respect of the number of shares that we issue and sell.

Lock-Up Agreements

We and the operating partnership have agreed that, during the period commencing on the date of this prospectus supplement and ending on the 45th day thereafter (the “Lock-up Period”), neither we nor the operating partnership will, without the prior written consent of the representatives, issue, sell, offer, contract or grant any option to sell, pledge, transfer or otherwise dispose of any shares of our common stock or common units or any securities exchangeable or exercisable for or convertible into common stock or common units, except that the foregoing restrictions will not apply to the following:

S-21

In addition, our directors and certain of our executive officers have agreed that they will not, without the prior written consent of the representatives, among other things, sell, offer, contract or grant any option to sell, pledge, transfer or otherwise dispose of any common stock or common units or securities exchangeable or exercisable for or convertible into shares of common stock or common units during the Lock-Up Period, except that the foregoing restrictions will not apply to the following:

provided, however, that the shares of common stock and other securities issued upon redemption of common units pursuant to the first bullet in this paragraph shall be subject to the restrictions described in this paragraph; and provided, further, that it shall be a condition to any transfer or pledge pursuant to the second, third or fourth bullets in this paragraph that the transferee or pledgee, as the case may be, executes and delivers to the representatives a written agreement to the effect that the shares of common stock or common units or securities exercisable or exchangeable for or convertible into shares of common stock transferred or pledged pursuant the second, third or fourth bullets in this paragraph shall be subject to the restrictions described in this paragraph.

New York Stock Exchange Listing

Our common stock is listed on the NYSE under the symbol “KRC.”

Price Stabilization and Short Positions

In order to facilitate this offering of shares of our common stock, the underwriters may engage in transactions that stabilize, maintain or otherwise affect the market price of our common stock. Specifically, the

S-22

underwriters may sell more shares than they are obligated to purchase under the underwriting agreement, creating a short position. A short sale is covered if the short position is no greater than the number of shares available for purchase by the underwriters under their option to purchase additional shares pursuant to the underwriting agreement. The underwriters may close out a covered short sale by exercising the option to purchase additional shares or purchasing shares in the open market. In determining the source of shares to close out a covered short sale, the underwriters may consider, among other things, the market price of our common stock compared to the price payable under the option to purchase additional shares. The underwriters may also sell shares in excess of the option to purchase additional shares, creating a naked short position. The underwriters must close out any naked short position by purchasing our common stock in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of our common stock in the open market after the date of pricing of this offering that could adversely affect investors who purchase in this offering.

As an additional means of facilitating this offering, the underwriters may bid for, and purchase, shares of our common stock in the open market to stabilize the price of our common stock. These stabilizing transactions may occur before or after the pricing of this offering. The underwriters may also impose a penalty bid. This occurs when a particular underwriter repays to the underwriters a portion of the underwriting discounts received by it because the representatives have repurchased shares sold by or for the account of such underwriter in stabilizing or short covering transactions.

The foregoing transactions, if commenced, may raise or maintain the market price of our common stock above independent market levels or prevent or retard a decline in the market price of our common stock.

The representatives of the underwriters have advised us that these transactions, if commenced, may be effected on the NYSE or otherwise. Neither we nor any of the underwriters makes any representation that the underwriters will engage in any of the transactions described above and these transactions, if commenced, may be discontinued without notice. Neither we nor any of the underwriters makes any representation or prediction as to the direction or magnitude of the effect that the transactions described above, if commenced, may have on the market price of our common stock.

Electronic Distribution

In connection with this offering, certain of the underwriters or securities dealers may distribute this prospectus supplement and the accompanying prospectus by electronic means, such as email. Certain of the underwriters may facilitate internet distribution for this offering to certain of their respective internet subscription customers. In addition, certain of the underwriters may allocate shares for sale to their respective online brokerage customers. An electronic prospectus supplement and the accompanying prospectus may be made available on the website maintained by any such underwriter. Other than this prospectus supplement and the accompanying prospectus in electronic format, the information on any such website is not part of, or incorporated by reference into, this prospectus supplement or the accompanying prospectus.

Conflicts of Interest

All of the proceeds from the sale of shares of our common stock offered by the forward sellers in this offering (excluding proceeds, if any, we may receive from the sale of shares of common stock to the underwriters in lieu of shares of common stock that would otherwise have been sold by the forward sellers) will be paid to the forward sellers. Because Barclays Capital Inc. and Citigroup Global Markets Inc., or their affiliates, as applicable, in their capacity as forward sellers, will receive more than 5% of the proceeds of this offering, Barclays Capital Inc. and Citigroup Global Markets Inc. are deemed to have a conflict of interest. However, because REITs are not subject to Rule 5121 of the Financial Industry Regulatory Authority, Inc., or FINRA, regarding conflicts of interest, the appointment of a “qualified independent underwriter” is not required in connection with this offering.

S-23

In addition, as described under “Use of Proceeds”, any net proceeds we may receive from the sale of any shares of common stock, if any, that we may sell the underwriters in lieu of shares that would otherwise have been sold by the forward sellers may be used to repay outstanding indebtedness. Affiliates of the underwriters participating in this offering are lenders under the operating partnership’s revolving credit facility and term loan facility and the underwriters and/or their respective affiliates may from time to time hold debt securities or other indebtedness of ours or any of our subsidiaries. To the extent that we use any such net proceeds to repay any of our outstanding indebtedness (including bank loans) held by any of the underwriters or their affiliates, they will receive proceeds from this offering through the repayment of that indebtedness. If 5% or more of such net proceeds (not including the underwriting discount) is used to repay indebtedness owed to at least one of the underwriters and/or affiliates of such underwriter, such underwriter or underwriters will also be deemed to have a conflict of interest. However, because REITs are not subject to FINRA Rule 5121 regarding conflicts of interest, the appointment of a “qualified independent underwriter” is not required in connection with this offering. For additional information, see “Use of Proceeds” above and “– Other Relationships” below.

Other Relationships

In addition to the matters discussed above under “—Conflicts of Interest,” some or all of the underwriters, forward sellers and forward purchasers and/or their respective affiliates have engaged in, and/or may in the future engage in, investment banking, commercial banking, financial advisory and/or other commercial dealings in the ordinary course of business with us, the operating partnership and/or other subsidiaries of ours, for which they have received and/or in the future may receive fees and commissions for these transactions or services.

In addition, in the ordinary course of their various business activities, the underwriters, forward sellers and forward purchasers and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers and such investment and securities activities may involve securities and/or instruments of ours or the operating partnership. To the extent that any of the underwriters, forward sellers or forward purchasers or any of their respective affiliates have lending relationships with us or the operating partnership or any of our other subsidiaries, they may also choose to hedge their credit exposure to us, the operating partnership or such subsidiary, as the case may be, consistent with their customary risk management policies. Typically, those underwriters, forward sellers or forward purchasers or such affiliates would hedge such exposure by entering into transactions, which may consist of either the purchase of credit default swaps or the creation of short positions in securities of us or the operating partnership. The underwriters and their respective affiliates may also make investment recommendations and/or publish or express independent research views in respect of securities or financial instruments of ours or the operating partnership and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

Selling Restrictions

No action has been taken in any jurisdiction (except in the United States) that would permit a public offering of the shares of common stock, or the possession, circulation or distribution of this prospectus supplement, the accompanying prospectus or any other material relating to us or the shares, where action for that purpose is required. Accordingly, the shares may not be offered or sold, directly or indirectly, and neither this prospectus supplement, the accompanying prospectus nor any other offering material or advertisements in connection with the shares may be distributed or published, in or from any country or jurisdiction except in compliance with any applicable rules and regulations of any such country or jurisdiction.

Each of the underwriters may arrange to sell the shares offered hereby in certain jurisdictions outside the United States, either directly or through affiliates, where they are permitted to do so.

S-24

Notice to Prospective Investors in Australia

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission (“ASIC”), in relation to this offering. This prospectus supplement and the accompanying prospectus do not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001 (the “Corporations Act”), and do not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

Any offer in Australia of the shares of common stock may only be made to persons (“Exempt Investors”) who are “sophisticated investors” (within the meaning of section 708(8) of the Corporations Act), “professional investors” (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the shares of common stock without disclosure to investors under Chapter 6D of the Corporations Act.

The shares of common stock applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under this offering, except in circumstances where disclosure to investors under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act. Any person acquiring shares of common stock must observe such Australian on-sale restrictions.

This prospectus supplement and the accompanying prospectus contain general information only and do not take account of the investment objectives, financial situation or particular needs of any particular person. They do not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement and the accompanying prospectus is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

Notice to Prospective Investors in the Dubai International Financial Centre

This prospectus supplement and the accompanying prospectus relate to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority (“DFSA”). This prospectus supplement and the accompanying prospectus are intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. They must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement or the accompanying prospectus nor taken steps to verify the information set forth herein or therein and has no responsibility for this prospectus supplement or the accompanying prospectus. The common stock to which this prospectus supplement and the accompanying prospectus relate may be illiquid and/or subject to restrictions on resale. Prospective purchasers of the common stock offered should conduct their own due diligence on the common stock. If you do not understand the contents of this prospectus supplement or the accompanying prospectus you should consult an authorized financial advisor.

Notice to Prospective Investors in the Netherlands

Neither this prospectus supplement, the accompanying prospectus or any free writing prospectus we may provide in connection with this offering is addressed to or intended for, and the shares of common stock

S-25

described in the prospectus supplement and the accompanying prospectus are not and will not be, directly or indirectly, offered, sold, transferred or delivered to, any individual or legal entity in the Netherlands except to individuals or entities that are qualified investors (gekwalificeerde beleggers) within the meaning of Article 1:1 of the Dutch Financial Supervision Act (Wet op het financieel toezicht, Wft). As a consequence no approved prospectus has to be published in the Netherlands pursuant to Article 3 of the European Directive 2003/71/EC as amended (including by Directive 2010/73/EU) and implemented in Netherlands law.

Notice to Prospective Investors in the United Kingdom

In relation to the United Kingdom, no offer of the common stock which is the subject of the offering has been, or will be, made to the public in the United Kingdom, other than under the following exemptions under the Financial Services and Markets Act 2000 as amended (“FSMA”):

provided that no such offer of the common stock referred to in (a) through (c) above shall result in a requirement for us or any underwriters to publish a prospectus pursuant to Section 85(1) of the FSMA.

For the purposes of this provision, the expression an “offer of the common stock to the public” in relation to any common stock means the communication in any form and by any means of sufficient information on the terms of the offer and the common stock to be offered so as to enable an investor to decide to purchase or subscribe the common stock, as fully defined in Section 102B of the FSMA.

Each person located in the United Kingdom to whom any offer of common stock is made or who receives any communication in respect of any offer of common stock, or who initially acquires any common stock, will be deemed to have represented, warranted, acknowledged and agreed to and with each underwriter and us that (1) it is a “qualified investor” within the meaning of Section 86 of the FSMA; and (2) in the case of any common stock acquired by it as a financial intermediary as that term is used Part VI of the FSMA, the common stock acquired by it in the offer has not been acquired on behalf of, nor has it been acquired with a view to its offer or resale to, persons other than qualified investors, or in circumstances in which the prior consent of the representatives has been given to the offer or resale; or where common stock has been acquired by it on behalf of persons in the United Kingdom other than qualified investors, the offer of that common stock to it is not treated under the FSMA as having been made to such persons.

We, the underwriters, our affiliates and the affiliates of the respective underwriters will rely upon the truth and accuracy of the foregoing representations, acknowledgments and agreements.

Neither this prospectus supplement nor the accompanying prospectus is a prospectus for the purposes of the FSMA and each of them has been prepared on the basis that any offer of common stock in the United Kingdom will be made pursuant to an exemption under the FSMA from the requirement to publish a prospectus for offers of common stock. Accordingly any person making or intending to make an offer in the United Kingdom of common stock which is the subject of the offering contemplated in this prospectus supplement and the accompanying prospectus may only do so in circumstances in which no obligation arises for us or any of the underwriters to publish a prospectus pursuant to Section 85(1) of the FSMA in relation to such offer. Neither we nor the underwriters have authorized, nor do we or they authorize, the making of any offer of common stock in circumstances in which an obligation arises for us or the underwriters to publish a prospectus for such offer.

No invitation or inducement to engage in investment activity (within the meaning of Section 21 of the FSMA) received by the underwriters in connection with the issue or sale of the common stock may be

S-26

communicated or caused to be communicated except in circumstances in which Section 21(1) of the FSMA does not apply to us. All applicable provisions of the FSMA must be complied with respect to anything done or to be done by the underwriters in relation to any common stock in, from or otherwise involving the United Kingdom.

In addition, this prospectus supplement and the accompanying prospectus are being distributed only to and are directed only at persons (i) who have professional experience in matters relating to investments falling within Article 19 (5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the “Order”) and/or (ii) who are high net worth companies or other persons falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as “relevant persons”). This prospectus supplement and the accompanying prospectus must not be acted on or relied on in the United Kingdom by persons who are not relevant persons. In the United Kingdom, any investment or investment activity to which this prospectus supplement and the accompanying prospectus relate is only available to, and will be engaged in with, relevant persons.

Notice to Prospective Investors in Canada

The common stock may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the common stock must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement or the accompanying prospectus (including any amendment hereto or thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory.

The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding conflicts of interest in connection with this offering.

S-27

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” the information we file with the SEC, which means that we can disclose important information to you by referring to those documents. The information incorporated by reference is an important part of this prospectus supplement and the accompanying prospectus. Any statement contained in this prospectus supplement, the accompanying prospectus or a document which is incorporated by reference in this prospectus supplement or the accompanying prospectus is automatically updated and superseded if information contained in this prospectus supplement or the accompanying prospectus, or information that we later file with the SEC prior to the termination of this offering that is incorporated by reference or deemed to be incorporated by reference herein or therein, modifies or replaces such statements. We incorporate by reference the following documents we filed with the SEC:

As described in this prospectus supplement under the caption “Supplemental United States Federal Income Tax Considerations,” the information appearing in the accompanying prospectus under the caption “United States Federal Income Tax Considerations” and in the Company’s and the operating partnership’s Current Report on Form 8-K (including the exhibits thereto) filed with the SEC on October 30, 2017 has been superseded and replaced in its entirety by the information appearing in the Company’s Current Report on Form 8-K (including the exhibit thereto) filed with the SEC on February 13, 2018. As described in this prospectus supplement under the caption “Supplemental Description of Capital Stock,” the information appearing in the accompanying prospectus under the captions “Description of Capital Stock” and “Certain Provisions of Maryland Law and of the Company’s Charter and Bylaws” has been supplemented and a portion of such information has been superseded by the information appearing in the Company’s Current Reports on Form 8-K (including the exhibits thereto) filed with the SEC on February 1, 2017 and August 23, 2017.

We are also incorporating by reference any additional documents that we file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act on or after the date of this prospectus supplement and before the termination of this offering. We are not, however, incorporating by reference any documents or portions thereof or exhibits thereto, whether specifically listed above or filed in the future, that are deemed to have been “furnished to,” rather than “filed” with the SEC, including our compensation committee report and performance graph included or incorporated by reference in any Annual Report on Form 10-K or proxy statement, or any information or related exhibits furnished pursuant to Items 2.02 or 7.01 of Form 8-K, or any exhibits filed pursuant to Item 9.01 of Form 8-K that are not deemed “filed” with the SEC.

To receive a free copy of any of the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, including exhibits, if they are specifically incorporated by reference in the documents, call or write Kilroy Realty Corporation, 12200 West Olympic Boulevard, Suite 200, Los Angeles, California 90064, Attention: Secretary (telephone (310) 481-8400).

S-28

LEGAL MATTERS

Certain legal matters in connection with this offering will be passed upon for us by Latham & Watkins LLP, Los Angeles, California. Certain legal matters relating to Maryland law, including the validity of the issuance of the shares of common stock offered by this prospectus supplement, and the accompanying prospectus, will be passed upon for us by Ballard Spahr LLP, Baltimore, Maryland. Sidley Austin LLP, San Francisco, California, will act as counsel for the underwriters, forward sellers and forward purchasers.

EXPERTS

The consolidated financial statements, and the related financial statement schedules, incorporated in this prospectus supplement by reference from Kilroy Realty Corporation’s Annual Report on Form 10-K for the year ended December 31, 2017, and the effectiveness of Kilroy Realty Corporation’s internal control over financial reporting have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports, which are incorporated herein by reference, which reports (1) express an unqualified opinion on the consolidated financial statements and financial statement schedules and (2) express an unqualified opinion on the effectiveness of internal control over financial reporting. Such consolidated financial statements and financial statement schedules have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

The consolidated financial statements, and the related financial statement schedules, incorporated in this prospectus supplement by reference from Kilroy Realty, L.P.’s Annual Report on Form 10-K for the year ended December 31, 2017, and the effectiveness of Kilroy Realty, L.P.’s internal control over financial reporting have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports, which are incorporated herein by reference, which reports (1) express an unqualified opinion on the consolidated financial statements and financial statement schedules and (2) express an unqualified opinion on the effectiveness of internal control over financial reporting. Such consolidated financial statements and financial statement schedules have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

S-29

PROSPECTUS

KILROY REALTY CORPORATION

Common Stock, Preferred Stock, Depositary Shares, Warrants and Guarantees

KILROY REALTY, L.P.

Debt Securities

We may offer from time to time in one or more series or classes (i) debt securities of Kilroy Realty, L.P. which may be fully and unconditionally guaranteed by Kilroy Realty Corporation, (ii) shares of Kilroy Realty Corporation’s common stock, par value $.01 per share, (iii) shares or fractional shares of Kilroy Realty Corporation’s preferred stock, par value $.01 per share, (iv) shares of Kilroy Realty Corporation’s preferred stock represented by depositary shares and (v) warrants to purchase preferred stock or common stock, referred to collectively in this prospectus as the offered securities, separately or together, in separate series in amounts, at prices and on terms to be set forth in one or more supplements to this prospectus.

The specific terms of the offered securities with respect to which this prospectus is being delivered will be set forth in the applicable prospectus supplement, along with any applicable modifications of or additions to the general terms of the debt securities as described in this prospectus, and will include, where applicable (i) in the case of debt securities and, as applicable, related guarantees, the specific terms of such debt securities, which may be either senior or subordinated, secured or unsecured, and related guarantees, (ii) in the case of common stock, any initial public offering price; (iii) in the case of preferred stock, the specific title and any dividend, liquidation, redemption, conversion, voting and other rights and any initial public offering price; (iv) in the case of depositary shares, the fractional or multiple shares of preferred stock represented by each such depositary share; and (v) in the case of warrants, the duration, offering price, exercise price and detachability. In addition, such specific terms may include limitations on actual or constructive ownership and restrictions on transfer of the offered securities, in each case as may be appropriate to preserve Kilroy Realty Corporation’s status as a real estate investment trust, or REIT, for federal income tax purposes.

The applicable prospectus supplement will also contain information, where applicable, about (i) certain United States federal income tax consequences relating to, and (ii) any listing on a securities exchange of, the offered securities covered by such prospectus supplement.

The securities may be offered directly, through agents we may designate from time to time or by, to or through underwriters or dealers. The securities also may be offered by securityholders, if so provided in a prospectus supplement hereto. We will provide specific information about any selling securityholders in one or more supplements to this prospectus. If any agents or underwriters are involved in the sale of any of the offered securities, their names, and any applicable purchase price, fee, commission or discount arrangement with or among them, will be set forth in, or will be calculable from the information set forth in, the applicable prospectus supplement. See “Plan of Distribution.” No offered securities may be sold without delivery of this prospectus and the applicable prospectus supplement describing the method and terms of the offering of such series of offered securities.

Kilroy Realty Corporation’s common stock is listed on the New York Stock Exchange, or NYSE, under the symbol “KRC.” On September 28, 2016, the last reported sales price of Kilroy Realty Corporation’s common stock on the NYSE was $69.55 per share.

Before you invest in the offered securities, you should consider the risks discussed in “Risk Factors” on page 1.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or completeness of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is September 29, 2016.

TABLE OF CONTENTS

Kilroy Realty, L.P., or the operating partnership, is a Delaware limited partnership. Kilroy Realty Corporation, or the Company or guarantor, is the sole general partner of the operating partnership. Unless otherwise expressly stated or the context otherwise requires, in this prospectus, “we,” “us” and “our” refer collectively to the Company, the operating partnership and the Company’s other subsidiaries, references to “Company common stock” or similar references refer to the common stock, par value $.01 per share, of the Company and references to “common units” or similar references refer to the common units of the operating partnership.

You should rely only on the information contained in this prospectus, the applicable prospectus supplement, the documents incorporated or deemed to be incorporated by reference in either and any free writing prospectus that we may provide you in connection with the offered securities. We have not authorized anyone to provide you with information or make any representation that is different. If anyone provides you with any additional or different information, you should not rely on it. Neither this prospectus nor the applicable prospectus supplement nor any such free writing prospectus is an offer to sell or a solicitation of an offer to buy any securities other than the registered securities to which they relate or an offer to sell or the solicitation of an offer to buy securities in any jurisdiction where, or to any person to whom, it is unlawful to make an offer or solicitation. You should not assume that the information contained in this prospectus, the applicable prospectus supplement, any document incorporated or deemed to be incorporated by reference in either or any free writing prospectus that we may provide you in connection with the offered securities is accurate on any date after the respective dates of those documents. Our business, financial condition, results of operations, funds from operations and prospects may have changed since those respective dates.

i

RISK FACTORS

Investment in the offered securities involves risks. Before acquiring any offered securities pursuant to this prospectus, you should carefully consider the information contained or incorporated by reference in this prospectus, in the applicable prospectus supplement or in any free writing prospectus that we may prepare in connection with the offered securities, including, without limitation, the risks set forth under the captions “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” (or similar captions) in Kilroy Realty Corporation’s and Kilroy Realty, L.P.’s most recent Annual Report on Form 10-K and subsequent Quarterly Reports on Form 10-Q, incorporated into this prospectus and the applicable prospectus supplement by reference, as updated in subsequent filings of Kilroy Realty Corporation and Kilroy Realty, L.P. with the Securities and Exchange Commission, or the SEC, under the Securities Exchange Act of 1934, as amended, or the Exchange Act, that are incorporated by reference in either. The occurrence of any of these risks could materially and adversely affect our business, financial condition, liquidity, results of operations, funds from operations and prospects and might cause you to lose all or a part of your investment in the offered securities. Please also refer to the section entitled “Forward-Looking Statements” included elsewhere in this prospectus and the applicable prospectus supplement.

FORWARD-LOOKING STATEMENTS

This prospectus and the applicable prospectus supplement, including the documents incorporated by reference in either, contain, and documents we subsequently file with the SEC and incorporate by reference in either may contain, certain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or Securities Act, and Section 21E of the Exchange Act, including information concerning our capital resources, portfolio performance, results of operations, projected future occupancy and rental rates, lease expirations, debt maturities, potential investments, strategies such as capital recycling, development and redevelopment activity, projected construction costs, projected construction commencement and completion dates, dispositions, future executive incentive compensation, pending, potential or proposed acquisitions, the anticipated use of proceeds from any offered securities, anticipated growth in our funds from operations and anticipated market conditions, demographics, and similar matters. Forward-looking statements can be identified by the use of words such as “believes,” “expects,” “projects,” “may,” “will,” “should,” “seeks,” “approximately,” “intends,” “plans,” “pro forma,” “estimates” or “anticipates” and the negative of these words and phrases and similar expressions that do not relate to historical matters. Forward-looking statements are based on our current expectations, beliefs and assumptions, and are not guarantees of future performance. Forward- looking statements are inherently subject to uncertainties, risks, changes in circumstances, trends and factors that are difficult to predict, many of which are outside of our control. Accordingly, actual performance, results and events may vary materially from those indicated in the forward-looking statements, and you should not rely on the forward-looking statements as predictions of future performance, results or events. Numerous factors could cause actual future performance, results and events to differ materially from those indicated in the forward-looking statements, including, among others:

1

The factors included in this prospectus and the applicable prospectus supplement, including the documents incorporated by reference in either, and documents we subsequently file with the SEC and incorporate by reference in either, are not exhaustive and additional factors could adversely affect our business and financial performance. For a discussion of additional risk factors, see the factors included under the caption “Risk Factors” in this prospectus, in the applicable prospectus supplement, in our and the operating partnership’s most recent Annual Report on Form 10-K, and in our and the operating partnership’s subsequent Quarterly Reports on Form 10-Q, as well as the other risks described in this prospectus and the applicable prospectus supplement and the documents incorporated by reference in either. All forward-looking statements are based on information that was available, and speak only, as of the date on which they were made. We assume no obligation to update any forward-looking statement that becomes untrue because of subsequent events, new information or otherwise, except to the extent we are required to do so in connection with our ongoing requirements under Federal securities laws.

2

CONSOLIDATED RATIO OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED DIVIDENDS

Kilroy Realty Corporation’s consolidated ratio of earnings to fixed charges and consolidated ratio of earnings to combined fixed charges and preferred dividends for each of the periods indicated was as follows:

We have computed the consolidated ratio of earnings to fixed charges for Kilroy Realty Corporation by dividing earnings by fixed charges. Earnings consist of income from continuing operations before the effect of noncontrolling interest plus fixed charges and amortization of capitalized interest, reduced by capitalized interest and loan costs and distributions on Series A cumulative redeemable preferred units prior to their redemption on August 15, 2012. Fixed charges consist of interest costs, whether expensed or capitalized, amortization of loan costs, an estimate of the interest within rental expense, and distributions on Series A cumulative redeemable preferred units prior to their redemption on August 15, 2012.

We have computed the consolidated ratio of earnings to combined fixed charges and preferred dividends for Kilroy Realty Corporation by dividing earnings by combined fixed charges and preferred dividends. Earnings consist of income from continuing operations before the effect of noncontrolling interest plus fixed charges and amortization of capitalized interest, reduced by capitalized interest and loan costs and distributions on Series A cumulative redeemable preferred units prior to their redemption on August 15, 2012. Fixed charges consist of interest costs, whether expensed or capitalized, amortization of loan costs, an estimate of the interest within rental expense, and distributions on Series A cumulative redeemable preferred units prior to their redemption on August 15, 2012. Preferred dividends consist of dividends on the Company’s 6.375% Series H Cumulative Redeemable Preferred Stock (the “Series H preferred stock”) and 6.875% Series G Cumulative Redeemable Preferred Stock (the “Series G preferred stock”) since their issuance on August 6, 2012 and March 16, 2012, respectively, and on the Company’s 7.50% Series F Cumulative Redeemable Preferred Stock and 7.80% Series E Cumulative Redeemable Preferred Stock prior to their redemption on April 16, 2012.

The computation of the consolidated ratio of earnings to fixed charges indicates that earnings were inadequate to cover fixed charges, calculated as described above, by approximately $14.6 million, $23.5 million and $26.8 million for the years ended December 31, 2013, 2012 and 2011, respectively.

The computation of the consolidated ratio of earnings to combined fixed charges and preferred dividends indicates that earnings were inadequate to cover fixed charges and preferred dividends, calculated as described above, by approximately $27.9 million, $34.1 million and $36.4 million for the years ended December 31, 2013, 2012 and 2011, respectively.

3

Kilroy Realty, L.P.’s consolidated ratio of earnings to fixed charges for each of the periods indicated was as follows:

We have computed the consolidated ratio of earnings to fixed charges for Kilroy Realty, L.P. by dividing earnings by fixed charges. Earnings consist of income from continuing operations before the effect of noncontrolling interest plus fixed charges and amortization of capitalized interest, reduced by capitalized interest and loan costs. Fixed charges consist of interest costs, whether expensed or capitalized, amortization of loan costs and an estimate of the interest within rental expense.

The computation of the consolidated ratio of earnings to fixed charges indicates that earnings were inadequate to cover fixed charges, calculated as described above, by approximately $14.6 million, $19.9 million and $21.2 million for the years ended December 31, 2013, 2012 and 2011, respectively.

4

THE COMPANY

We are a self-administered REIT active in premier office submarkets along the West Coast. We own, develop, acquire and manage real estate assets, consisting primarily of Class A properties in the coastal regions of Los Angeles, Orange County, San Diego County, the San Francisco Bay Area and greater Seattle, which we believe have strategic advantages and strong barriers to entry. Class A real estate encompasses attractive and efficient buildings of high quality that are attractive to tenants, are well-designed and constructed with above-average material, workmanship and finishes and are well-maintained and managed.

As of June 30, 2016, our stabilized office portfolio was comprised of 102 office properties, which encompassed an aggregate of approximately 13.7 million rentable square feet. As of June 30, 2016, these properties were approximately 95.5% occupied by 526 tenants. Our stabilized portfolio includes all of our properties with the exception of development and redevelopment properties currently under construction or committed for construction, “lease-up” properties, real estate assets held for sale, undeveloped land and our recently completed residential property. As of June 30, 2016, we had one development project under construction that is expected to encompass approximately 700,000 aggregate rentable square feet upon completion. We define “redevelopment properties” as those properties for which we expect to spend significant development and construction costs on the existing or acquired buildings pursuant to a formal plan, the intended result of which is a higher economic return on the property. As of June 30, 2016, we had no redevelopment properties. We define “lease-up” properties as office properties we recently developed or redeveloped that have not yet reached 95% occupancy and are within one year following cessation of major construction activities. As of June 30, 2016, we had two development projects in “lease-up,” encompassing approximately 443,000 aggregate rentable square feet, two properties held for sale and eight development sites, representing approximately 70 gross acres of undeveloped land.

Kilroy Realty Corporation is a Maryland corporation organized to qualify as a REIT under the Internal Revenue Code of 1986, as amended, or the Code, which owns its interests in all of its properties through the operating partnership and Kilroy Realty Finance Partnership, L.P., both of which are Delaware limited partnerships. We generally conduct substantially all of our operations through the operating partnership in which, as of June 30, 2016, Kilroy Realty Corporation owned an approximate 97.2% general partnership interest. The remaining approximately 2.8% common limited partnership interest in the operating partnership as of June 30, 2016 was owned by non-affiliated investors and certain executive officers and directors of Kilroy Realty Corporation.

The Company’s outstanding common stock and preferred stock are listed on the NYSE. The Company’s common stock is listed under the symbol “KRC,” the Company’s 6.875% Series G Cumulative Redeemable Preferred Stock is listed under the symbol “KRC-PG,” and the Company’s 6.375% Series H Cumulative Redeemable Preferred Stock is listed under the symbol “KRC-PH.”

Our principal executive offices are located at 12200 West Olympic Boulevard, Suite 200, Los Angeles, California 90064. Our telephone number is (310) 481-8400.

5

USE OF PROCEEDS

We intend to use the net proceeds from the sale of the offered securities as set forth in the applicable prospectus supplement. We will not receive any of the proceeds from sales of offered securities by selling securityholders.

DESCRIPTION OF DEBT SECURITIES AND RELATED GUARANTEES

This section describes the general terms and provisions of the operating partnership’s debt securities. When our operating partnership offers to sell a particular series of debt securities, we will describe the specific terms of the series in a supplement to this prospectus, along with any applicable modifications of or additions to the general terms of the debt securities as described in this prospectus, including the terms of any related guarantees by the Company and the terms, if any, on which a series of debt securities may be convertible into or exchangeable for other securities. To the extent the information contained in the prospectus supplement differs from this summary description, you should rely on the information in the prospectus supplement.

The debt securities may be offered either separately, or together with, or upon the conversion or exercise of or in exchange for, other securities described in this prospectus. Debt securities may be the operating partnership’s senior, senior subordinated or subordinated obligations and may be issued in one or more series. Unless otherwise specified in the applicable prospectus supplement, the debt securities will be the operating partnership’s direct, unsecured senior obligations and will rank equally in right of payment with all of its other senior unsecured indebtedness.

Unless otherwise specified in a prospectus supplement, the debt securities will be issued under the indenture dated as of March 1, 2011, as amended and supplemented by a supplemental indenture thereto dated as of July 5, 2011 (as so amended and supplemented, the “indenture”), among the operating partnership, the Company and U.S. Bank National Association, as trustee. The indenture contains the full legal text of the matters described in this section. We have summarized select portions of the indenture below. The summary is not complete and is subject to and qualified in its entirety by reference to all the provisions of the indenture, including definitions of the terms used in the indenture. Whenever we refer to particular sections or defined terms of the indenture in this prospectus or in a prospectus supplement, those sections or defined terms are incorporated by reference into this prospectus or the applicable prospectus supplement, and this summary also is subject to and qualified by reference to the description of the particular terms of a particular series of debt securities described in the applicable prospectus supplement. The form of the indenture has been filed as an exhibit to the Registration Statement of which this prospectus is a part and you should read the indenture for provisions that may be important to you. Capitalized terms used in the summary and not defined herein have the meanings specified in the indenture.

As used in this “Description of Debt Securities and Related Guarantees,” references to the “operating partnership,” “we,” “our” or “us” refer solely to Kilroy Realty, L.P. and not to any of its subsidiaries and references to the “Company” or “guarantor” refer solely to Kilroy Realty Corporation and not to any of its subsidiaries, unless otherwise expressly stated or the context otherwise requires.

General

The terms of each series of debt securities will be established by or pursuant to a resolution of the Company’s board of directors and set forth or determined in the manner provided in a resolution of the Company’s board of directors, in an officer’s certificate or by a supplemental indenture. The particular terms of each series of debt securities, along with any applicable modifications of or additions to the general terms of the debt securities as described in this prospectus, will be described in a prospectus supplement relating to such series (including any pricing supplement or term sheet). A prospectus supplement, pricing supplement or term sheet may change any of the terms of the debt securities described in this prospectus.

6

Unless we state otherwise in the applicable prospectus supplement, we can issue an unlimited amount of the operating partnership’s debt securities under the indenture that may be in one or more series with the same or various maturities, at par, at a premium, or at a discount. We will set forth in a prospectus supplement (including any pricing supplement or term sheet) relating to any series of debt securities being offered, the aggregate principal amount and the following terms of the debt securities, if applicable:

7

As discussed above, we may issue debt securities of the operating partnership that provide for an amount less than their stated principal amount to be due and payable upon declaration of acceleration of their maturity pursuant to the terms of the indenture. In addition, we may denominate the purchase price of any of the debt securities in a foreign currency or currencies or a foreign currency unit or units, and the principal of and any premium and interest on any series of debt securities may be payable in a foreign currency or currencies or a foreign currency unit or units. The applicable prospectus supplement will provide you with information on the federal income tax considerations and other special considerations applicable to any such debt securities.

No Protection in the Event of a Change of Control

Unless we state otherwise in the applicable prospectus supplement, the debt securities of any series will not contain any provisions which may afford holders of the debt securities of such series protection in the event the operating partnership or the Company has a change of control or in the event of a highly leveraged transaction (whether or not such transaction results in a change of control), which could adversely affect holders of debt securities.

Covenants

We will set forth in the applicable prospectus supplement any restrictive covenants applicable to any issue of any series of debt securities.

Merger, Consolidation and Sale of Assets

Unless we state otherwise in the applicable prospectus supplement, the operating partnership and the Company may consolidate with, or sell, lease or convey all or substantially all of their respective assets to, or merge with or into, any other entity, provided that the following conditions are met:

8

Upon any such merger, consolidation or conveyance, the resulting, surviving or transferee person shall succeed to, and may exercise every right and power of, the operating partnership or the Company, as the case may be, under the indenture.

Events of Default

Unless we state otherwise in the applicable prospectus supplement, the indenture provides that the following events are “Events of Default” with respect to any series of debt securities:

9

A supplemental indenture or officer’s certificate establishing the terms of a particular series of debt securities may delete, modify or add to the Events of Default described above.

If an Event of Default with respect to the debt securities of a particular series occurs and is continuing (other than an Event of Default specified in the last bullet above, which shall result in an automatic acceleration), then in every case the trustee or the holders of not less than 25% in principal amount of the outstanding debt securities of such series may declare the principal amount of, and accrued and unpaid interest on, all of the debt securities of such series to be due and payable immediately by written notice thereof to the operating partnership and the Company (and to the trustee if given by the holders). However, at any time after the declaration of acceleration (or automatic acceleration) with respect to the debt securities of such series has occurred, but before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of not less than a majority in principal amount of the debt securities of such series outstanding may rescind and annul the declaration and its consequences if:

The indenture also provides that the holders of not less than a majority in principal amount of the outstanding debt securities of any series may waive any past default or Event of Default with respect to the debt securities of such series and its consequences, except, among other things, a default:

The trustee will be required to give notice to the holders of the debt securities of any particular series within 90 days of a default under the indenture with respect to the debt securities of such series known to a responsible officer (as defined in the indenture) of the trustee unless the default has been cured or waived; provided, however, that the trustee may withhold notice to the holders of the debt securities of such series of any default with respect to the debt securities of such series (except a default in the payment of the principal of or premium, if any or interest on the debt securities of such series) if responsible officers of the trustee in good faith determine the withholding to be in the interest of the holders of the debt securities of such series; and provided, further, that in the case of a default with respect to the debt securities of any series of the character specified in the penultimate bullet point of the first paragraph under this caption “Events of Default,” no such notice to holders of debt securities of such series shall be given until at least 60 days after the occurrence thereof.

The indenture provides that no holder of the debt securities of a particular series may institute any action or proceedings, judicial or otherwise, with respect to the indenture or for any remedy thereunder, unless:

10

This provision will not prevent, however, any holder of the debt securities of any series from instituting suit for the enforcement of payment of the principal of or premium if any, or interest on such debt securities on or after the respective due dates thereof.

Subject to provisions in the indenture relating to its duties in case of default, the trustee will be under no obligation to exercise any of its rights or powers under the indenture at the request or direction of any holders of debt securities of any series then outstanding under the indenture, unless the holders of debt securities of such series shall have offered to the trustee reasonable security or indemnity. The holders of not less than a majority in principal amount of the outstanding debt securities of any series shall have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or of exercising any trust or power conferred upon the trustee with respect to the debt securities of such series. However, the trustee may refuse to follow any direction which is in conflict with any law or the indenture or which may involve the trustee in personal liability or be unduly prejudicial to the holders of the debt securities of such series not joining therein.

Within 120 days after the close of each fiscal year, the operating partnership and the Company must deliver a certificate of an officer certifying to the trustee whether or not the officer has knowledge of any default under the indenture and, if so, specifying each default and the nature and status thereof.

Modification, Waiver and Meetings

Unless we state otherwise in the applicable prospectus supplement, modifications and amendments of the indenture will be permitted to be made pursuant to a supplemental indenture entered into by the operating partnership, the Company and the trustee with the consent of the holders of not less than a majority in principal amount of all outstanding debt securities of each series affected by such supplemental indenture (including consent obtained in connection with a tender offer or exchange offer for the outstanding debt securities of such series); provided, however, that no modification or amendment may, without the consent of the holder of each debt security affected thereby:

11

Notwithstanding the foregoing, modifications and amendments of the indenture will be permitted to be made by supplemental indenture executed by the operating partnership, the Company and the trustee without the consent of any holder of the debt securities for, among other things, any of the following purposes:

The operating partnership and the Company may omit in any particular instance to comply with certain specified covenants in the indenture with respect to the debt securities of any series (which, if expressly stated in the prospectus supplement applicable to the debt securities of such series, may include any additional covenants specified in such prospectus supplement) if the holders of at least a majority in principal amount of all outstanding debt securities of such series waive such compliance. In determining whether the holders of the

12

requisite principal amount of outstanding debt securities have given any request, demand, authorization, direction, notice, consent or waiver under the indenture or whether a quorum is present at a meeting of holders of debt securities, the indenture provides that debt securities owned by the operating partnership, the Company or any other obligor upon the debt securities or the guarantees thereof or any affiliate of the operating partnership, the Company, or of any other such obligor shall be disregarded.

The indenture contains provisions for convening meetings of the holders of debt securities of any series. A meeting of the holders of debt securities of any series will be permitted to be called at any time by the trustee, and also, upon request, by the operating partnership or the holders of at least 25% in principal amount of the outstanding debt securities of such series, in any case upon notice given as provided in the indenture. Except for any consent that must be given by the holder of each debt security affected by certain modifications and amendments of the indenture, any resolution presented at a meeting or adjourned meeting duly reconvened at which a quorum is present will be permitted to be adopted by the affirmative vote of the holders of a majority in principal amount of the outstanding debt securities of such series; provided, however, that, except for any consent that must be given by the holder of each debt security affected as referred to above, any resolution with respect to any request, demand, authorization, direction, notice, consent, waiver or other action that may be made, given or taken by the holders of a specified percentage, which is less than a majority, in principal amount of the outstanding debt securities of such series may be adopted at a meeting or adjourned meeting duly reconvened at which a quorum is present by the affirmative vote of the holders of the specified percentage in principal amount of the outstanding debt securities of such series. Any resolution passed or decision taken at any meeting of holders of debt securities of any series duly held in accordance with the indenture will be binding on all holders of the debt securities of such series. The quorum at any meeting called to adopt a resolution, and at any reconvened meeting, of the debt securities of any series will be holders of a majority in principal amount of the outstanding debt securities of such series; provided, however, that if any action is to be taken at the meeting with respect to a request, demand, authorization, direction, notice, consent, waiver or other action which may be given by the holders of not less than a specified percentage in principal amount of the outstanding debt securities of such series, holders of the specified percentage in principal amount of the outstanding debt securities of such series will constitute a quorum with respect to that matter. In the absence of a quorum at the reconvening of any adjourned meeting, such adjourned meeting may be further adjourned for a period of not less than ten days; at the reconvening of any meeting adjourned or further adjourned for lack of a quorum, the persons entitled to vote 25% in aggregate principal amount of the then outstanding debt securities of such series shall constitute a quorum.

Notwithstanding the foregoing provisions, if any action is to be taken at a meeting of holders of debt securities of any series with respect to any request, demand, authorization, direction, notice, consent, waiver or other action that the indenture expressly provides may be taken by holders of such series and one or more additional series acting collectively and voting together as a single class, there shall be no minimum quorum requirement for that meeting and the principal amount of outstanding debt securities of all such series that are entitled to vote in favor of that request, demand, authorization, direction, notice, consent, waiver or other action shall be taken into account in determining whether such action has been made, given or taken under the indenture.

Discharge, Defeasance and Covenant Defeasance

Unless we state otherwise in the applicable prospectus supplement, the indenture shall cease to be of further effect with respect to any series of debt securities, and the Company shall be released from its guarantee of the debt securities of such series (subject to the survival of a limited number of specified provisions) when:

13

The indenture provides that the operating partnership may elect:

To effect legal defeasance or covenant defeasance, the operating partnership will be required to make an irrevocable deposit with the trustee, in trust for such purpose, of money and/or Government Obligations that, through the scheduled payment of interest and principal in accordance with their terms, will provide money in an amount sufficient to pay and discharge the principal, premium, if any, and interest on the debt securities of such series on the scheduled due dates or the applicable redemption date, as the case may be, in accordance with the terms of the indenture and the debt securities of such series. Upon any legal defeasance (but not covenant defeasance) the Company will be released from its guarantee of the debt securities of such series.

The trust described in the preceding paragraph may only be established if, among other things:

In the event we effect covenant defeasance with respect to the debt securities of any series, then any failure by the operating partnership or the Company to comply with any covenant as to which there has been covenant defeasance will not constitute an Event of Default. However, if the debt securities of such series are declared due

14

and payable because of the occurrence of any other Event of Default, the amount of monies and/or Government Obligations deposited with the trustee to effect such covenant defeasance may not be sufficient to pay amounts due on the debt securities of such series at the time of any acceleration resulting from such Event of Default. However, the operating partnership and the Company would remain liable to make payment of such amounts due at the time of acceleration.

Governing Law

The indenture, the debt securities and any guarantees endorsed on the certificates evidencing the debt securities will be governed by, and construed in accordance with, the internal laws of the State of New York.

Book-entry System

The Global Notes

The debt securities of each series will be initially issued in the form of one or more registered debt securities in global form, without interest coupons, or the global notes. Upon issuance, each of the global notes will be deposited with the trustee as custodian for The Depository Trust Company, or DTC, and registered in the name of Cede & Co., as nominee of DTC.

Ownership of beneficial interests in a global note will be limited to persons who have accounts with DTC, or DTC participants, or persons who hold interests through DTC participants. We expect that under procedures established by DTC:

Beneficial interests in global notes may not be exchanged for notes in physical, certificated form except in the limited circumstances described below.

Book-entry Procedures for the Global Notes

All interests in the global notes will be subject to the operations and procedures of DTC. We provide the following summary of those operations and procedures solely for the convenience of investors. The operations and procedures of DTC are controlled by that settlement system and may be changed at any time. None of the operating partnership, the Company or the applicable underwriters are responsible for those operations or procedures.

DTC has advised us that it is:

15

DTC was created to hold securities for its participants and to facilitate the clearance and settlement of securities transactions between its participants through electronic book-entry changes to the accounts of its participants. DTC’s participants include securities brokers and dealers, including underwriters, banks and trust companies, clearing corporations and other organizations. Indirect access to DTC’s system is also available to others such as banks, brokers, dealers and trust companies; these indirect participants clear through or maintain a custodial relationship with a DTC participant, either directly or indirectly. Investors who are not DTC participants may beneficially own securities held by or on behalf of DTC only through DTC participants or indirect participants in DTC.

So long as DTC’s nominee is the registered owner of a global note, that nominee will be considered the sole owner or holder of the debt securities represented by that global note for all purposes under the indenture. Except as provided below, owners of beneficial interests in a global note:

As a result, each investor who owns a beneficial interest in a global note of any series must rely on the procedures of DTC to exercise any rights of a holder of debt securities of such series under the indenture (and, if the investor is not a participant or an indirect participant in DTC, on the procedures of the direct, or, if applicable, indirect DTC participant through which the investor owns its interest).

Payments of principal, premium, if any, and interest with respect to the debt securities represented by a global note will be made by the trustee to DTC or DTC’s nominee as the registered holder of the global note. Neither the operating partnership, the Company nor the trustee will have any responsibility or liability for the payment of amounts to owners of beneficial interests in a global note, for any aspect of the records relating to or payments made on account of those interests by DTC, or for maintaining, supervising or reviewing any records of DTC relating to those interests.

Payments by participants and indirect participants in DTC to the owners of beneficial interests in a global note will be governed by standing instructions and customary industry practice and will be the responsibility of those participants or indirect participants and DTC.

Transfers between participants in DTC will be effected under DTC’s procedures and will be settled in same-day funds.

Certificated Notes

If the Debt securities of any series are initially issued as global notes, debt securities of such series in physical, certificated form will be issued and delivered to each person that DTC identifies as a beneficial owner of the debt securities of such series only if:

16

DESCRIPTION OF CAPITAL STOCK

The following is a summary of some of the terms and provisions of the capital stock of Kilroy Realty Corporation. The following description does not purport to be complete and is subject to, and qualified in its entirety by reference to, the provisions of the Company’s charter (including, without limitation, the articles supplementary (the “Articles Supplementary”) establishing the terms of the Company’s 6.875% Series G Cumulative Redeemable Preferred Stock (the “Series G preferred stock”) and 6.375% Series H Cumulative Redeemable Preferred Stock (the “Series H preferred stock”)) incorporated by reference to our SEC filings. See “Where You Can Find More Information.” As used in this “Description of Capital Stock,” references to the “Company,” “we,” “our” or “us” refer solely to Kilroy Realty Corporation and not to any of its subsidiaries, unless otherwise expressly stated or the context otherwise requires.

Common Stock

General

The Company’s charter authorizes us to issue 150,000,000 shares of common stock, par value $.01 per share. As of September 23, 2016, we had 92,270,393 shares of common stock outstanding. The number of outstanding shares of common stock excludes the following as of September 23, 2016: (i) 286,000 shares of common stock issuable upon exercise of options granted under our equity compensation plans; (ii) 1,353,349 additional shares of common stock reserved and available for issuance under our equity compensation plans; (iii) 2,043,999 shares of common stock underlying restricted stock units awarded under our stock award deferral program; (iv) 2,631,276 shares of common stock issuable upon redemption of common units of the operating partnership outstanding; and (v) a total of up to 9,236,100 shares of our common stock (subject to certain anti-dilution and other potential adjustments) issuable upon conversion of our Series G preferred stock and Series H preferred stock following a “Change of Control” (as defined in the terms of the Series G preferred stock and Series H preferred stock, respectively) of us.

Shares of our common stock:

We may pay distributions on shares of the Company’s common stock, subject to the preferential rights of the Company’s Series G preferred stock, the Company’s Series H preferred stock and any other series or class of capital stock that we may issue in the future with rights to dividends and other distributions senior to the Company’s common stock. However, we may only pay distributions when the board of directors (in its sole discretion) authorizes a distribution out of legally available funds.

The Company’s board of directors may:

17

Certain Provisions of the Maryland General Corporation Law

Under the Maryland General Corporation Law, or the MGCL, the Company’s stockholders are generally not liable for our debts or obligations. If we liquidate, we will first pay all debts and other liabilities, including debts and liabilities arising out of the Company’s status as general partner of the operating partnership, and, second, any preferential distributions on any outstanding shares of our preferred stock. Each holder of the Company’s common stock then will share ratably in our remaining assets. All shares of the Company’s common stock have equal distribution, liquidation and voting rights, and have no preference or exchange rights, subject to the ownership limits in the Company’s charter or as permitted by the board of directors pursuant to executed agreements waiving these ownership limits with respect to specific stockholders.

Under the MGCL, we generally require approval by the Company’s stockholders by the affirmative vote of at least two-thirds of the votes entitled to vote before we can:

Because the term “substantially all” of a company’s assets is not defined in the MGCL, it is subject to Maryland common law and to judicial interpretation and review in the context of the unique facts and circumstances of any particular transaction. Although the MGCL allows the Company’s charter to establish a lesser percentage of affirmative votes by the Company’s stockholders for approval of those actions, the Company’s charter does not include such a provision.

Preferred Stock

The Company’s charter authorizes us to issue 30,000,000 shares of preferred stock, par value $.01 per share. Of the 30,000,000 authorized shares of preferred stock, we have classified and designated 4,600,000 shares as Series G preferred stock and 4,000,000 shares as Series H preferred stock. As of September 23, 2016, 4,000,000 shares of the Company’s Series G preferred stock are issued and outstanding and 4,000,000 shares of Series H preferred stock are issued and outstanding.

We may classify, designate and issue additional shares of currently authorized shares of preferred stock, in one or more classes or series, as authorized by the board of directors without the prior consent of the Company’s stockholders. The board of directors may grant the holders of preferred stock of any class or series preferences, powers and rights—voting or otherwise—senior to the rights of holders of shares of the Company’s common stock. The board of directors can authorize the issuance of currently authorized shares of preferred stock with terms and conditions that could have the effect of delaying or preventing a change of control transaction that might involve a premium price for holders of shares of the Company’s common stock or otherwise be in their

18

best interest. All shares of preferred stock which are issued and are or become outstanding are or will be fully paid and nonassessable. Before we may issue any shares of preferred stock of any class or series, the MGCL and the Company’s charter require the board of directors to determine the following with respect to such class or series:

6.875% Series G Cumulative Redeemable Preferred Stock

General

Of the Company’s 30,000,000 authorized preferred shares, 4,600,000 shares have been classified and designated as 6.875% Series G Cumulative Redeemable Preferred Stock. Of these shares, as of September 23, 2016, 4,000,000 are issued and outstanding.

Dividends

Each share of Series G preferred stock is entitled to receive, when, as, and if authorized by the Company’s board of directors and declared by us, out of funds legally available for the payment of dividends, cumulative cash dividends at the rate of 6.875% of the $25.00 per share liquidation preference per annum (equivalent to $1.71875 per annum per share), payable quarterly in arrears on February 15, May 15, August 15 and November 15 of each year.

Except as provided in the immediately following paragraph, unless full cumulative dividends for all past dividend periods on the Series G preferred stock have been or contemporaneously are declared and paid or declared and a sum sufficient for the payment thereof is set apart for such payment, no dividends (other than in shares of the Company’s common stock or shares of any other class or series of stock of the Company ranking junior to the Series G preferred stock as to dividends and as to the distribution of assets upon liquidation, dissolution and winding up of the Company) shall be declared or paid or set aside for payment nor shall any other distribution be declared or made on the Company’s common stock or any other class or series of stock of the Company ranking junior to or on a parity with the Series G preferred stock as to dividends or as to the distribution of assets upon liquidation, dissolution or winding up of the Company, nor shall any shares of the Company’s common stock or any other class or series of stock of the Company ranking junior to or on a parity with the Series G preferred stock as to dividends or as to the distribution of assets upon liquidation, dissolution or winding up of the Company be redeemed, purchased or otherwise acquired for any consideration (or any amounts be paid to or made available for a sinking fund for the redemption of any shares of any such stock) by the Company (except by conversion into or exchange for shares of the Company’s common stock or shares of any other class or series of stock of the Company ranking junior to the Series G preferred stock as to dividends and as to the distribution of assets upon liquidation, dissolution and winding up of the Company); provided, however, that the foregoing shall not prevent the purchase or acquisition of shares of the Company’s stock to preserve the Company’s status as a real estate investment trust, or REIT, for federal and/or state income tax purposes. With

19

respect to the Series G preferred stock, all references to “past dividend periods” shall mean, as of any date, dividend periods ending on or prior to such date, and with respect to shares of any other class or series of stock ranking on a parity as to dividends with the Series G preferred stock, “past dividend periods” shall mean, as of any date, dividend periods with respect to such other class or series of stock ending on or prior to such date.

When full cumulative dividends for all past dividend periods are not paid in full (or a sum sufficient for the full payment is not set apart) upon the shares of Series G preferred stock and when full cumulative dividends for all past dividend periods are not paid in full (or a sum sufficient for such full payment is not so set apart) upon the shares of any other class or series of the Company’s stock ranking on a parity as to dividends with the Series G preferred stock, then all dividends declared on shares of Series G preferred stock and any other outstanding classes or series of the Company’s stock ranking on a parity as to dividends with the Series G preferred stock shall be declared pro rata so that the amount of dividends declared per share on the Series G preferred stock and such other classes or series of stock ranking on a parity as to dividends with the Series G preferred stock shall in all cases bear to each other the same ratio that accumulated and unpaid dividends per share on the shares of Series G preferred stock and such other classes or series of stock ranking on a parity as to dividends with the Series G preferred stock (which, in the case of any such other class or series of stock ranking on a parity as to dividends with the Series G preferred stock, shall not include any accumulation in respect of unpaid dividends for past dividend periods if such other class or series of stock ranking on a parity as to dividends with the Series G preferred stock does not have a cumulative dividend) bear to each other.

Ranking

The Series G preferred stock will, with respect to dividends and rights upon the distribution of assets upon the Company’s voluntary or involuntary liquidation, dissolution or winding-up, rank:

Redemption

The Series G preferred stock will not be redeemable before March 27, 2017, except to preserve our status as a REIT for federal and/or state income tax purposes and except as described below upon the occurrence of a Series G Change of Control (as defined below). On and after March 27, 2017, we may, at our option, redeem any or all of the shares of the Series G preferred stock, for cash, at $25.00 per share plus, subject to exceptions, any accrued and unpaid dividends to but excluding the date fixed for redemption.

Upon the occurrence of a Series G Change of Control, we may, at our option, at any time or from time to time, redeem any or all of the shares of Series G preferred stock, within 120 days after the first date on which such Series G Change of Control occurred, for cash, at $25.00 per share plus, subject to exceptions, any accrued and unpaid dividends to but excluding the date fixed for redemption. If, prior to the Series G Change of Control Conversion Date (as defined below), we have provided or provide notice of our election to redeem some or all of the shares of Series G preferred stock (whether pursuant to our optional redemption right described in the paragraph above or the special optional redemption right described in this paragraph), the holders of Series G preferred stock will not have the conversion right described below under “—Conversion Rights” with respect to the shares of Series G preferred stock called for redemption.

A “Series G Change of Control” is when the following have occurred and are continuing:

20

The “Series G Change of Control Conversion Date” is the date the Series G preferred stock is to be converted into the Company’s common stock, which will be a business day selected by the Company that is no fewer than 20 days nor more than 35 days after the date on which the Company provides a notice of the occurrence of the Series G Change of Control that describes the resulting Series G Change of Control Conversion Right to the holders of Series G preferred stock.

Conversion Rights

Upon the occurrence of a Series G Change of Control, each holder of Series G preferred stock will have the right, which we refer to as the Series G Change of Control Conversion Right (unless, prior to the Series G Change of Control Conversion Date, the Company has provided notice of its election to redeem some or all of the shares of Series G preferred stock held by such holder pursuant to the redemption provisions described above under “—Redemption,” in which case such holder will have the right only with respect to shares of Series G preferred stock that are not called for redemption) to convert some or all of the Series G preferred stock held by such holder on the Series G Change of Control Conversion Date, into a number of shares of the Company’s common stock per share of Series G preferred stock equal to the lesser of:

subject, in each case, to provisions for the receipt of alternative consideration under specified circumstances as set forth in the Articles Supplementary for the Series G preferred stock.

The “Series G Common Stock Price” is (i) if the consideration to be received in the Series G Change of Control by the holders of the Company’s common stock is solely cash, the amount of cash consideration per share of the Company’s common stock or (ii) if the consideration to be received in the Series G Change of Control by holders of the Company’s common stock is other than solely cash (x) the average of the closing sale prices per share of the Company’s common stock (or, if no closing sale price is reported, the average of the closing bid and ask prices per share or, if more than one in either case, the average of the average closing bid and the average closing ask prices per share) for the ten consecutive trading days immediately preceding, but not including, the date on which such Series G Change of Control occurred as reported on the principal U.S. securities exchange on which the Company’s common stock is then traded, or (y) the average of the last quoted

21

bid prices for the Company’s common stock in the over-the-counter market as reported by Pink OTC Markets Inc. or similar organization for the ten consecutive trading days immediately preceding, but not including, the date on which such Series G Change of Control occurred, if the Company’s common stock is not then listed for trading on a U.S. securities exchange.

No Maturity, Sinking Fund or Mandatory Redemption

The Series G preferred stock has no maturity date, and the Company is not required to redeem the Series G preferred stock at any time. Accordingly, the shares of Series G preferred stock will remain outstanding indefinitely, unless the Company decides, at its option, to exercise its redemption rights or otherwise repurchase them or they become convertible and are converted in the manner set forth in Articles Supplementary for the Series G preferred stock. None of the Series G preferred stock is subject to any sinking fund.

Limited Voting Rights

Holders of Series G preferred stock do not have any voting rights except as set forth below. Whenever dividends on any shares of Series G preferred stock are in arrears for six or more quarterly periods, whether or not consecutive, the holders of Series G preferred stock will have the right to vote as a single class with all other classes or series of stock ranking on parity with the Series G preferred stock upon which like voting rights have been conferred and are exercisable for the election of two additional directors to the board of directors. The election will take place at:

When all of the dividends in arrears have been paid or declared and provided for in full, the right of holders of the Series G preferred stock to elect those two directors will cease and, unless there are one or more other classes or series of the Company’s preferred stock ranking on a parity with the Series G preferred stock upon which like voting rights have been conferred and are exercisable, the term of office of the two directors shall automatically terminate and the number of directors constituting the board of directors shall be reduced accordingly.

In addition, so long as any shares of Series G preferred stock are outstanding, without the consent or affirmative vote of at least two-thirds of the shares of Series G preferred stock then outstanding, the Company may not:

22

provided that any amendment to the Company’s charter to increase the number of authorized shares of stock or the creation or issuance of any other class or series of preferred stock or any increase in the number of authorized or outstanding shares of Series G preferred stock or any other class or series of stock, in each case ranking on a parity with or junior to the Series G preferred stock with respect to payment of dividends and the distribution of assets upon liquidation, dissolution and winding up, shall not be deemed to materially and adversely affect any right, preference, privilege or voting power of the Series G preferred stock.

On each matter on which holders of Series G preferred stock are entitled to vote, each share of Series G preferred stock will be entitled to one vote, except that when shares of any other class or series of the Company’s preferred stock have the right to vote with the Series G preferred stock as a single class on any matter, the Series G preferred stock and the shares of each such other class or series will have one vote for each $50.00 of liquidation preference (excluding accrued and unpaid dividends), resulting in each share of Series G preferred stock being entitled to one-half of a vote under such circumstances.

Except as expressly stated in the Articles Supplementary for the Series G preferred stock, the Series G preferred stock will not have any relative, participating, optional or other special voting rights or powers and the consent of the holders shall not be required for the taking of any corporate action.

The voting provisions above will not apply if, at or prior to the time when the act with respect to which the vote would otherwise be required would occur, all outstanding shares of Series G preferred stock shall have been redeemed or called for redemption upon proper notice and sufficient funds shall have been irrevocably deposited in trust to effect the redemption.

Liquidation Preference

Upon any voluntary or involuntary liquidation, dissolution or winding-up of the Company, each share of Series G preferred stock is entitled to receive, out of our assets legally available for distribution to stockholders, a liquidation distribution of $25.00 per share, plus any accrued but unpaid dividends, in preference to any of the Company’s common stock or any other class or series of the Company’s stock ranking junior to the Series G preferred stock, but subject to the preferential rights of any class or series of our preferred stock ranking senior to the Series G preferred stock.

6.375% Series H Cumulative Redeemable Preferred Stock

General

Of the Company’s 30,000,000 authorized preferred shares, 4,000,000 shares have been classified and designated as 6.375% Series H Cumulative Redeemable Preferred Stock. Of these shares, as of September 23, 2016, 4,000,000 are issued and outstanding.

Dividends

Each share of Series H preferred stock is entitled to receive, when, as, and if authorized by the Company’s board of directors and declared by us, out of funds legally available for the payment of dividends, cumulative

23

cash dividends at the rate of 6.375% of the $25.00 per share liquidation preference per annum (equivalent to $1.59375 per annum per share), payable quarterly in arrears on February 15, May 15, August 15 and November 15 of each year.

Except as provided in the immediately following paragraph, unless full cumulative dividends for all past dividend periods on the Series H preferred stock have been or contemporaneously are declared and paid or declared and a sum sufficient for the payment thereof is set apart for such payment, no dividends (other than in shares of the Company’s common stock or shares of any other class or series of stock of the Company ranking junior to the Series H preferred stock as to dividends and as to the distribution of assets upon liquidation, dissolution and winding up of the Company) shall be declared or paid or set aside for payment nor shall any other distribution be declared or made on the Company’s common stock or any other class or series of stock of the Company ranking junior to or on a parity with the Series H preferred stock as to dividends or as to the distribution of assets upon liquidation, dissolution or winding up of the Company, nor shall any shares of the Company’s common stock or any other class or series of stock of the Company ranking junior to or on a parity with the Series H preferred stock as to dividends or as to the distribution of assets upon liquidation, dissolution or winding up of the Company be redeemed, purchased or otherwise acquired for any consideration (or any amounts be paid to or made available for a sinking fund for the redemption of any shares of any such stock) by the Company (except by conversion into or exchange for shares of the Company’s common stock or shares of any other class or series of stock of the Company ranking junior to the Series H preferred stock as to dividends and as to the distribution of assets upon liquidation, dissolution and winding up of the Company); provided, however, that the foregoing shall not prevent the purchase or acquisition of shares of the Company’s stock to preserve the Company’s status as a REIT for federal and/or state income tax purposes. With respect to the Series H preferred stock, all references to “past dividend periods” shall mean, as of any date, dividend periods ending on or prior to such date, and with respect to shares of any other class or series of stock ranking on a parity as to dividends with the Series H preferred stock, “past dividend periods” shall mean, as of any date, dividend periods with respect to such other class or series of stock ending on or prior to such date.

When full cumulative dividends for all past dividend periods are not paid in full (or a sum sufficient for the full payment is not set apart) upon the shares of Series H preferred stock and when full cumulative dividends for all past dividend periods are not paid in full (or a sum sufficient for such full payment is not so set apart) upon the shares of any other class or series of the Company’s stock ranking on a parity as to dividends with the Series H preferred stock, then all dividends declared on shares of Series H preferred stock and any other outstanding classes or series of the Company’s stock ranking on a parity as to dividends with the Series H preferred stock shall be declared pro rata so that the amount of dividends declared per share on the Series H preferred stock and such other classes or series of stock ranking on a parity as to dividends with the Series H preferred stock shall in all cases bear to each other the same ratio that accumulated and unpaid dividends per share on the shares of Series H preferred stock and such other classes or series of stock ranking on a parity as to dividends with the Series H preferred stock (which, in the case of any such other class or series of stock ranking on a parity as to dividends with the Series H preferred stock, shall not include any accumulation in respect of unpaid dividends for past dividend periods if such other class or series of stock ranking on a parity as to dividends with the Series H preferred stock does not have a cumulative dividend) bear to each other.

Ranking

The Series H preferred stock will, with respect to dividends and rights upon the distribution of assets upon the Company’s voluntary or involuntary liquidation, dissolution or winding-up, rank:

24

Redemption

The Series H preferred stock will not be redeemable before August 15, 2017, except to preserve our status as a REIT for federal and/or state income tax purposes and except as described below upon the occurrence of a Series H Change of Control (as defined below). On and after August 15, 2017, we may, at our option, redeem any or all of the shares of the Series H preferred stock, for cash, at $25.00 per share plus, subject to exceptions, any accrued and unpaid dividends to but excluding the date fixed for redemption.

Upon the occurrence of a Series H Change of Control, we may, at our option, at any time or from time to time, redeem any or all of the shares of Series H preferred stock, within 120 days after the first date on which such Series H Change of Control occurred, for cash, at $25.00 per share plus, subject to exceptions, any accrued and unpaid dividends to but excluding the date fixed for redemption. If, prior to the Series H Change of Control Conversion Date (as defined below), we have provided or provide notice of our election to redeem some or all of the shares of Series H preferred stock (whether pursuant to our optional redemption right described in the paragraph above or the special optional redemption right described in this paragraph), the holders of Series H preferred stock will not have the conversion right described below under “—Conversion Rights” with respect to the shares of Series H preferred stock called for redemption.

A “Series H Change of Control” is when the following have occurred and are continuing:

The “Series H Change of Control Conversion Date” is the date the Series H preferred stock is to be converted into the Company’s common stock, which will be a business day selected by the Company that is no fewer than 20 days nor more than 35 days after the date on which the Company provides a notice of the occurrence of the Series H Change of Control that describes the resulting Series H Change of Control Conversion Right to the holders of Series H preferred stock.

Conversion Rights

Upon the occurrence of a Series H Change of Control, each holder of Series H preferred stock will have the right, which we refer to as the Series H Change of Control Conversion Right (unless, prior to the Series H Change of Control Conversion Date, the Company has provided notice of its election to redeem some or all of the shares of Series H preferred stock held by such holder pursuant to the redemption provisions described above under “—Redemption,” in which case such holder will have the right only with respect to shares of Series H preferred stock that are not called for redemption) to convert some or all of the Series H preferred stock held by such holder on the Series H Change of Control Conversion Date, into a number of shares of the Company’s common stock per share of Series H preferred stock equal to the lesser of:

25

subject, in each case, to provisions for the receipt of alternative consideration under specified circumstances as set forth in the Articles Supplementary for the Series H preferred stock.

The “Series H Common Stock Price” is (i) if the consideration to be received in the Series H Change of Control by the holders of the Company’s common stock is solely cash, the amount of cash consideration per share of the Company’s common stock or (ii) if the consideration to be received in the Series H Change of Control by holders of the Company’s common stock is other than solely cash (x) the average of the closing sale prices per share of the Company’s common stock (or, if no closing sale price is reported, the average of the closing bid and ask prices per share or, if more than one in either case, the average of the average closing bid and the average closing ask prices per share) for the ten consecutive trading days immediately preceding, but not including, the date on which such Series H Change of Control occurred as reported on the principal U.S. securities exchange on which the Company’s common stock is then traded, or (y) the average of the last quoted bid prices for the Company’s common stock in the over-the-counter market as reported by Pink OTC Markets Inc. or similar organization for the ten consecutive trading days immediately preceding, but not including, the date on which such Series H Change of Control occurred, if the Company’s common stock is not then listed for trading on a U.S. securities exchange.

No Maturity, Sinking Fund or Mandatory Redemption

The Series H preferred stock has no maturity date, and the Company is not required to redeem the Series H preferred stock at any time. Accordingly, the shares of Series H preferred stock will remain outstanding indefinitely, unless the Company decides, at its option, to exercise its redemption rights or otherwise repurchase them or they become convertible and are converted in the manner set forth in Articles Supplementary for the Series H preferred stock. None of the Series H preferred stock is subject to any sinking fund.

Limited Voting Rights

Holders of Series H preferred stock do not have any voting rights except as set forth below. Whenever dividends on any shares of Series H preferred stock are in arrears for six or more quarterly periods, whether or not consecutive, the holders of Series H preferred stock will have the right to vote as a single class with all other classes or series of stock ranking on parity with the Series H preferred stock upon which like voting rights have been conferred and are exercisable for the election of two additional directors to the board of directors. The election will take place at:

26

When all of the dividends in arrears have been paid or declared and provided for in full, the right of holders of the Series H preferred stock to elect those two directors will cease and, unless there are one or more other classes or series of the Company’s preferred stock ranking on a parity with the Series H preferred stock upon which like voting rights have been conferred and are exercisable, the term of office of the two directors shall automatically terminate and the number of directors constituting the board of directors shall be reduced accordingly.

In addition, so long as any shares of Series H preferred stock are outstanding, without the consent or affirmative vote of at least two-thirds of the shares of Series H preferred stock then outstanding, the Company may not:

provided that any amendment to the Company’s charter to increase the number of authorized shares of stock or the creation or issuance of any other class or series of preferred stock or any increase in the number of authorized or outstanding shares of Series H preferred stock or any other class or series of stock, in each case ranking on a parity with or junior to the Series H preferred stock with respect to payment of dividends and the distribution of assets upon liquidation, dissolution and winding up, shall not be deemed to materially and adversely affect any right, preference, privilege or voting power of the Series H preferred stock.

On each matter on which holders of Series H preferred stock are entitled to vote, each share of Series H preferred stock will be entitled to one vote, except that when shares of any other class or series of the Company’s preferred stock have the right to vote with the Series H preferred stock as a single class on any matter, the Series H preferred stock and the shares of each such other class or series will have one vote for each $50.00 of liquidation preference (excluding accrued and unpaid dividends), resulting in each share of Series H preferred stock being entitled to one-half of a vote under such circumstances.

Except as expressly stated in the Articles Supplementary for the Series H preferred stock, the Series H preferred stock will not have any relative, participating, optional or other special voting rights or powers and the consent of the holders shall not be required for the taking of any corporate action.

The voting provisions above will not apply if, at or prior to the time when the act with respect to which the vote would otherwise be required would occur, all outstanding shares of Series H preferred stock shall have been redeemed or called for redemption upon proper notice and sufficient funds shall have been irrevocably deposited in trust to effect the redemption.

27

Liquidation Preference

Upon any voluntary or involuntary liquidation, dissolution or winding-up of the Company, each share of Series H preferred stock is entitled to receive, out of our assets legally available for distribution to stockholders, a liquidation distribution of $25.00 per share, plus any accrued but unpaid dividends, in preference to any of the Company’s common stock or any other class or series of the Company’s stock ranking junior to the Series H preferred stock, but subject to the preferential rights of any class or series of our preferred stock ranking senior to the Series H preferred stock.

Restrictions on Ownership and Transfer of the Company’s Capital Stock

Internal Revenue Code Requirements

To maintain the Company’s tax status as a REIT, five or fewer “individuals,” as that term is defined in the Code, which includes certain entities, may not own, actually or constructively, more than 50% in value of the Company’s issued and outstanding capital stock at any time during the last half of a taxable year. Constructive ownership provisions in the Code determine if any individual or entity constructively owns the Company’s capital stock for purposes of this requirement. In addition, 100 or more persons must beneficially own the Company’s capital stock during at least 335 days of a taxable year or during a proportionate part of a short taxable year. Also, rent from tenants in which we actually or constructively own a 10% or greater interest is not qualifying income for purposes of the gross income tests of the Code. To help ensure we meet these tests, the Company’s charter restricts the acquisition and ownership of shares of the Company’s capital stock.

Transfer Restrictions in the Company’s Charter

Subject to exceptions specified therein, the Company’s charter provides that no holder may own, either actually or constructively under the applicable constructive ownership provisions of the Code:

In addition, because rent from tenants in which we actually or constructively own a 10% or greater interest is not qualifying rent for purposes of the gross income tests under the Code, the Company’s charter provides that no holder may own, either actually or constructively by virtue of the constructive ownership provisions of the Code, which differ from the constructive ownership provisions used for purposes of the preceding sentence:

We refer to the limits described in this paragraph and the preceding paragraph, together, as the “ownership limits.”

The constructive ownership provisions set forth in the Code are complex, and may cause shares of the Company’s capital stock owned actually or constructively by a group of related individuals and/or entities to be

28

constructively owned by one individual or entity. As a result, the acquisition of shares of the Company’s capital stock in an amount that does not exceed the ownership limits, or the acquisition of an interest in an entity that actually or constructively owns the Company’s capital stock, could, nevertheless cause that individual or entity, or another individual or entity, to own constructively shares in excess of the ownership limits and thus violate the ownership limits described above or otherwise permitted by the Company’s board of directors.

The Company’s charter permits the board of directors to waive the ownership limits with respect to a particular stockholder if the board of directors:

As a condition of this waiver, the Company’s board of directors may require opinions of counsel satisfactory to it and/or undertakings or representations from the applicant with respect to preserving the Company’s REIT status. The board of directors has waived the ownership limit applicable to the Company’s common stock for John B. Kilroy, Sr. and John Kilroy, members of their families and some of their affiliated entities, allowing them to own up to 19.6% of the Company’s common stock. However, the board of directors conditioned this waiver upon the receipt of undertakings and representations from Messrs. Kilroy which it believed were reasonably necessary to conclude that the waiver would not cause us to fail to qualify and maintain the Company’s status as a REIT.

In addition to the foregoing ownership limits, the Company’s charter provides that no holder may own, either actually or constructively under the applicable attribution rules of the Code, any shares of any class of the Company’s capital stock if, as a result of this ownership:

Under the Company’s charter, any person who acquires or attempts or intends to acquire actual or constructive ownership of the Company’s shares of capital stock that violate any of the foregoing restrictions on transferability and ownership must give us notice immediately and provide us with any other information that we may request to determine the effect of the transfer on the Company’s status as a REIT. The foregoing restrictions on transferability and ownership will not apply if the Company’s board of directors determines that it is no longer in the Company’s best interest to attempt to qualify, or to continue to qualify, as a REIT.

Effect of Violation of Ownership Limits and Transfer Restrictions

The Company’s charter provides that if any attempted transfer of the Company’s capital stock or any other event would result in any person violating the ownership limits described above, unless otherwise permitted by the board of directors, then the purported transfer will be void ab initio and of no force or effect with respect to the attempted transferee as to that number of shares in excess of the applicable ownership limit, and the transferee shall acquire no right or interest in the excess shares. The Company’s charter further provides that in the case of any event other than a purported transfer, the person or entity holding record title to any of the excess shares shall cease to own any right or interest in the excess shares.

The Company’s charter provides that if any transfer or other event occurs that, if effective, would result in any person owning shares of Company’s capital stock in violation of the ownership limit described above, the

29

number of shares of capital stock that otherwise would cause such person to violate the ownership limit (the “excess shares”) will be transferred automatically to a trust, the beneficiary of which will be a qualified charitable organization selected by us or, if for any reason that transfer is not automatically effective, then the transfer of such excess shares shall be void ab initio and the purported transferee will not have any rights in such excess shares. The automatic transfer will be effective as of the close of business on the business day prior to the date of the violative transfer.

The trustee of the charitable trust must:

Excess shares transferred to the charitable trust shall be deemed to have been offered for sale to us at a price per share equal to the lesser of the price paid by the prohibited transferee or owner for the excess shares (or, if the event which resulted in the transfer to the charitable shares did not involve the purchase of the applicable stock for fair value, the market price of such shares on the day of the event which resulted in the transfer of such shares to the charitable trust) and the market price on the date we accept such offer. We will have the right to accept such offer until the charitable trust has sold the excess shares as described above.

The trustee shall be designated by us and be unaffiliated with us and any prohibited transferee or owner. Prior to a sale of any excess shares by the trust, the trustee will receive, in trust for the beneficiary, all dividends and other distributions paid by us with respect to the excess shares, and may also exercise all voting rights with respect to the excess shares.

The Company’s charter provides that, subject to Maryland law, effective as of the date that the shares have been transferred to the trust, the trustee shall have the authority, at the trustee’s sole discretion:

However, if we have already taken irreversible corporate action, then the trustee may not rescind and recast the vote. Any dividend or other distribution paid to the prohibited transferee or owner, prior to our discovery that the shares had been automatically transferred to a trust as described above, must be repaid to the trustee upon demand for distribution to the beneficiary of the trust. If the transfer to the trust as described above is not automatically effective, for any reason, to prevent violation of the applicable ownership limit or as otherwise permitted by the board of directors, then the Company’s charter provides that the transfer of the excess shares will be void ab initio.

If shares of capital stock are transferred to any person in a manner which would cause us to be beneficially owned by fewer than 100 persons, the Company’s charter provides that the transfer shall be null and void in its entirety, and the intended transferee will acquire no rights to the stock.

30

If the Company’s board of directors shall at any time determine in good faith that a person has acquired, intends to acquire or own, has attempted to acquire or own, or may acquire or own the Company’s capital stock in violation of the limits described above, the Company’s charter provides that the board of directors shall take actions to refuse to give effect to or to prevent the ownership or acquisition, including, but not limited to:

All certificates representing shares of the Company’s capital stock bear a legend referring to the restrictions described above.

All persons who own at least a specified percentage of the outstanding shares of the Company’s stock must file with us a completed questionnaire annually containing information about their ownership of the shares, as set forth in the applicable Treasury regulations. Under current Treasury regulations, the percentage is between 0.5% and 5.0%, depending on the number of record holders of the Company’s shares. In addition, each stockholder may be required to disclose to us in writing information about the actual and constructive ownership of the Company’s shares as the board of directors deems necessary to comply with the provisions of the Code applicable to a REIT or to comply with the requirements of any taxing authority or governmental agency.

These ownership limitations could discourage a takeover or other transaction in which holders of some, or a majority, of the Company’s shares of capital stock might receive a premium for their shares over the then prevailing market price or which stockholders might believe to be otherwise in their best interest.

Transfer Agent and Registrar for Shares of Capital Stock

Computershare Shareowner Services LLC is the transfer agent and registrar for shares of the Company’s preferred stock and common stock.

31

DESCRIPTION OF WARRANTS

We may issue warrants for the purchase of the Company’s preferred stock or common stock. Warrants may be issued independently or together with any other offered securities offered by the applicable prospectus supplement and may be attached to or separate from such offered securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between the Company and a warrant agent specified in the applicable prospectus supplement. The warrant agent will act solely as our agent in connection with the warrants of such series and will not assume any obligation or relationship of agency or trust for or with any provisions of the warrants offered hereby. Further terms of the warrants and the applicable warrant agreements will be set forth in the applicable prospectus supplement. As used in this “Description of Warrants,” references to the “Company,” “we,” “our” or “us” refer solely to Kilroy Realty Corporation and not to any of its subsidiaries, unless otherwise expressly stated or the context otherwise requires.

The applicable prospectus supplement will describe the terms of the warrants in respect of which this prospectus is being delivered, including, where applicable, the following:

Copies of the applicable form of warrant agreement and warrant may be obtained from us upon request, and the statements made within this prospectus relating to the warrant agreement and warrant to be issued pursuant to the warrant agreement are summaries of certain anticipated provisions, and do not purport to be complete and are subject to, and qualified in their entirety by reference to, all of the provisions of the applicable warrant agreement and related warrants.

32

DESCRIPTION OF DEPOSITARY SHARES

We may, at our option, elect to offer fractional or multiple shares of preferred stock, rather than single shares of preferred stock. In the event we exercise this option, we may issue depository receipts evidencing depositary shares, each of which will represent a fraction or multiple of, to be described in an applicable prospectus supplement, of a share of a particular series of preferred stock. The preferred stock represented by depositary shares will be deposited under a deposit agreement between us and a bank or trust company selected by us. Subject to the terms of the deposit agreement, each owner of a depositary share will, in general, be entitled, in proportion to the applicable fraction or multiple of a share of preferred stock represented by the depositary share, to all of the rights and preferences of the preferred stock or other equity stock represented thereby, including any dividend, voting, redemption, conversion or liquidation rights. For a description of our common stock and preferred stock, see the descriptions in this prospectus under the heading “Description of Capital Stock.” As used in this “Description of Depositary Shares,” references to the “Company,” “we,” “our” or “us” refer solely to Kilroy Realty Corporation and not to any of its subsidiaries, unless otherwise expressly stated or the context otherwise requires.

The depositary shares will be evidenced by depositary receipts issued pursuant to the deposit agreement. The particular terms of the depositary shares offered by the applicable prospectus supplement will be described in the prospectus supplement, which may also include a discussion of certain U.S. federal income tax consequences.

Copies of the applicable form of deposit agreement and depositary receipt may be obtained from us upon request, and the statements made within this prospectus relating to the deposit agreement and the depositary receipt to be issued pursuant to the deposit agreement are summaries of certain anticipated provisions, and do not purport to be complete and are subject to, and qualified in their entirety by reference to, all of the provisions of the applicable deposit agreement and related depositary receipts.

33

DESCRIPTION OF MATERIAL PROVISIONS OF THE PARTNERSHIP AGREEMENT OF KILROY REALTY, L.P.

The following is a summary of certain terms and provisions of the Seventh Amended and Restated Agreement of Limited Partnership of the operating partnership, which we refer to, together with any subsequent amendments, supplements or restatements thereof, as the “partnership agreement.” The following description does not purport to be complete and is subject to, and qualified in its entirety by reference to, the provisions of the partnership agreement. For more detail, you should refer to the partnership agreement itself, which is incorporated by reference to our SEC filings. See “Where You Can Find More Information.”

Management of the Partnership

The operating partnership is a Delaware limited partnership. The Company is the sole general partner of the operating partnership and conducts substantially all of its business through the operating partnership.

As the sole general partner of the operating partnership, the Company exercises exclusive and complete discretion in the day-to-day management and control of the operating partnership. Subject to certain exceptions set forth in the partnership agreement, the Company can cause the operating partnership to enter into certain major transactions including acquisitions, dispositions and refinancings and cause changes in its line of business, capital structure and distribution policies. Limited partners may not transact business for, or participate in the management activities or decisions of, the operating partnership, except as provided in the partnership agreement and as required by applicable law.

The operating partnership has both preferred limited partnership interests and common limited partnership interests. As of September 23, 2016, the operating partnership had issued and outstanding 4,000,000 6.875% Series G Cumulative Redeemable Preferred Units, or the Series G preferred units, 4,000,000 6.375% Series H Cumulative Redeemable Preferred Units, or the Series H preferred units, all of which were held by the Company, and 2,631,276 common units. In this discussion, We refer collectively to the Series G preferred units, the Series H preferred units and any other preferred units the operating partnership may issue in the future as preferred units, and to the preferred units and the common units as the units.

Indemnification of the Company’s Officers and Directors

To the extent permitted by applicable law, the partnership agreement provides indemnity to the Company, as general partner, and its officers, directors, employees, agents and any other persons the Company may designate. Similarly, the partnership agreement limits the Company’s liability, as well as that of its officers, directors, employees and agents, to the operating partnership.

Transferability of Partnership Interests

Generally, the Company may not voluntarily withdraw from or transfer or assign its interest in the operating partnership without the consent of the holders of at least 60% of the common units including the Company’s interest. The limited partners may, without the consent of the general partner, transfer, assign, sell, encumber or otherwise dispose of their units in the operating partnership to family members, affiliates (as defined under federal securities laws) and charitable organizations and as collateral in connection with certain lending transactions, and, with the consent of the general partner, may also transfer, assign or sell their units to accredited investors. In each case, the transferee must agree to assume the transferor’s obligations under the partnership agreement. This transfer is also subject to the Company’s right of first refusal to purchase the limited partner’s units for our benefit.

In addition, without the Company’s consent, limited partners may not transfer their units:

34

The Company may not engage in any “termination transaction” without the approval of at least 60% of the common units in the operating partnership, including the Company’s general partnership interest in the operating partnership. Termination transactions consist of:

In connection with a termination transaction, all common limited partners must either receive, or have the right to elect to receive, for each common unit an amount of cash, securities or other property equal to the product of:

If, in connection with a termination transaction, a purchase, tender or exchange offer is made to holders of Company common stock, and the common stockholders accept the purchase, tender or exchange offer, each holder of common units must either receive, or must have the right to elect to receive, the greatest amount of cash, securities or other property which that holder would have received if immediately prior to the purchase, tender or exchange offer it had exercised its right to redeem common units, received shares of Company common stock in exchange for its common units, and accepted the purchase, tender or exchange offer.

The Company also may merge or otherwise combine its assets with another entity with the approval of at least 60% of the common units if:

35

The board of directors of the Company, in the Company’s capacity as general partner, will reasonably determine relative fair market values and rights, preferences and privileges of the limited partners as of the time of the termination transaction. These values may not be less favorable to the limited partners than the relative values reflected in the terms of the termination transaction.

The Company must use commercially reasonable efforts to structure termination transactions to avoid causing the common limited partners to recognize gain for federal income tax purposes by virtue of the occurrence of or their participation in the termination transaction. In addition, the operating partnership must use commercially reasonable efforts to cooperate with the common limited partners to minimize any taxes payable in connection with any repayment, refinancing, replacement or restructuring of indebtedness, or any sale, exchange or other disposition of its assets.

Issuance of Additional Units Representing Partnership Interests

As sole general partner of the operating partnership, the Company has the ability to cause the operating partnership to issue additional units representing general and limited partnership interests. These units may include units representing preferred limited partnership interests, subject to the approval rights of holders of the Series G preferred units with respect to the issuance of preferred units ranking senior to the Series G preferred units and holders of the Series H preferred units with respect to the issuance of preferred units ranking senior to the Series H preferred units.

Capital Contributions by the Company to the Operating Partnership

The Company may borrow additional funds in excess of the funds available from borrowings or capital contributions from a financial institution or other lender or through public or private debt offerings. The Company may then lend these funds to the operating partnership on the same terms and conditions that applied to the Company. In some cases, the Company may instead contribute these funds as an additional capital contribution to the operating partnership and increase its interest in the operating partnership and decrease the interests of the limited partners.

The Effect of Awards Granted Under Our Stock Incentive Plans

The Company may issue shares of common stock (including restricted Company common stock) to employees and other service providers of the operating partnership and/or its subsidiaries Kilroy Services, LLC or Kilroy Realty TRS, Inc., which we refer to collectively as the services companies, as applicable, in respect of

36

services provided to such entity, pursuant to awards granted under the Company’s 1997 Stock Option and Incentive Plan, as amended, the Company’s 2006 Incentive Award Plan, as amended, or any other equity incentive award plan maintained by the Company from time to time.

Issuances of any such shares of Company common stock are treated as follows: (i) upon the issuance of the shares (or, with respect to restricted Company common stock, upon the vesting of such shares) a number of operating partnership units equal to the number of shares of Company common stock issued (or vested), are transferred by the operating partnership to the Company; (ii) any amounts paid by an employee or other service provider of the operating partnership or services companies, as applicable, to the Company to purchase such shares of Company common stock are transferred by the Company to the operating partnership or services companies, as applicable; and (iii) shares of Company common stock received by the employee or other service provider of the operating partnership or services companies, as applicable, are treated as compensation paid by the operating partnership or the services companies, as applicable, to the employee or other service provider (to the extent that the value of such shares at the time of transfer or subsequent vesting exceeds the amount paid for them).

Any distributions made to employees or other service providers of the operating partnership or services companies by the Company in respect of unvested shares of Company common stock are reimbursed to the Company by the operating partnership or services companies, as applicable, and are treated as compensation paid directly by the operating partnership or the services companies, as applicable. Unvested shares of Company common stock that are forfeited prior to vesting are returned to the Company by the employee or other service provider. In addition, any amounts paid for such shares are returned by the operating partnership or services companies, as applicable, to the Company. To the extent that an employee or other service provider provides services to more than one of the Company, the operating partnership, the services companies or any subsidiary, the Company may, in its discretion, allocate the payment or issuance of shares among such entities.

The foregoing description assumes that no employee or other service provider of the Company, the operating partnership or the services companies has made (or will make) an election under Section 83(b) of the Code.

Tax Matters that Affect the Operating Partnership

The Company has the authority under the partnership agreement to make tax elections under the Code on the operating partnership’s behalf.

Allocations of Net Income and Net Losses to Partners

The net income of the operating partnership will generally be allocated:

37

Net losses of the operating partnership will generally be allocated:

Notwithstanding the foregoing, the partnership agreement generally provides that the operating partnership’s adjusted net income (as defined in the partnership agreement) will first be allocated to the holders of the operating partnership’s Series G preferred units and the Series H preferred units and any other preferred units that the operating partnership may issue in the future to the extent of their preferred returns, with the remaining items of net income or net loss allocated according to the provisions described above. The allocations described above are subject to compliance with the provisions of Sections 704(b) and 704(c) of the Code and the associated Treasury regulations.

Operations and Management of the Operating Partnership

The operating partnership must be operated in a manner that will enable the Company to maintain its qualification as a REIT and avoid any federal income tax liability. The partnership agreement provides that the Company will determine from time to time, but not less frequently than quarterly, the net operating cash revenues of the operating partnership, as well as net sales and refinancing proceeds, pro rata in accordance with the partners respective percentage interests, subject to the distribution preferences with respect to the Series G preferred units and the Series H preferred units and any other preferred units that the operating partnership may issue in the future. The partnership agreement further provides that the operating partnership will assume and pay when due, or reimburse the Company for payment of, all expenses that the Company incurs relating to the ownership and operation of, or for the benefit of, the operating partnership and all costs and expenses relating to the Company’s operations.

Term of the Partnership Agreement

The operating partnership will continue in full force and effect until December 31, 2095, or until sooner dissolved in accordance with the terms of the partnership agreement.

6.875% Series G Cumulative Redeemable Preferred Units

Distributions

Each Series G preferred unit is entitled to receive cumulative preferential distributions payable on or before the 15th day of February, May, August and November of each year at a rate of 6.875% per annum of the $25.00 stated value of a Series G preferred unit (equivalent to $1.71875 per annum). The cumulative preferential distributions will be paid in preference to any payment made on any other class or series of partnership interest of the operating partnership, other than the Series H preferred units and any other class or series of partnership interest expressly designated as ranking on parity with or senior to the Series G preferred units.

38

Ranking

The Series G preferred units rank:

Redemption

The Series G preferred units will not be redeemable before March 27, 2017, except under circumstances intended to preserve the Company’s status as a REIT for federal and/or state income tax purposes or upon the occurrence of a Series G Change of Control (as defined above under “Description of Capital Stock—6.875% Series G Cumulative Redeemable Preferred Stock”). On and after March 27, 2017, the Series G preferred units may be redeemed at a redemption price, payable in cash, equal to the sum of $25.00 plus any accumulated and unpaid distributions to the date of redemption per Series G preferred unit. In addition, upon the occurrence of a Series G Change of Control, the Series G preferred units may be redeemed at a redemption price equal to the sum of $25.00 plus accumulated and unpaid distributions to the date of redemption per Series G preferred unit.

Conversion Rights

The Series G preferred units may be exchanged for common units upon a Series G Change of Control, all on the terms and subject to the conditions and exceptions described in the partnership agreement.

Liquidation Preference

The distribution and income allocation provisions of the partnership agreement have the effect of providing each Series G preferred unit with a liquidation preference equal to $25.00 per unit, plus any accumulated but unpaid distributions, in preference to any other class or series of partnership interest other than those interests expressly designated as ranking on a parity with or senior to the Series G preferred units.

6.375% Series H Cumulative Redeemable Preferred Units

Distributions

Each Series H preferred unit is entitled to receive cumulative preferential distributions payable on the 15th day of February, May, August and November of each year at a rate of 6.375% per annum of the $25.00 stated value of a Series H preferred unit (equivalent to $1.59375 per annum). The cumulative preferential distributions will be paid in preference to any payment made on any other class or series of partnership interest of the operating partnership, other than the Series G preferred units and any other class or series of partnership interest expressly designated as ranking on parity with or senior to the Series H preferred units.

Ranking

The Series H preferred units rank:

39

Redemption

The Series H preferred units will not be redeemable before August 15, 2017, except under circumstances intended to preserve the Company’s status as a real estate investment trust for federal and/or state income tax purposes or upon the occurrence of a Series H Change of Control (as defined above under “Description of Capital Stock—6.375% Series H Cumulative Redeemable Preferred Stock”). On and after August 15, 2017, the Series H preferred units may be redeemed at a redemption price payable in cash, equal to the sum of $25.00 plus any accumulated and unpaid distributions to the date of redemption per Series H preferred unit. In addition, upon the occurrence of a Series H Change of Control, the Series H preferred units may be redeemed at a redemption price equal to the sum of $25.00 plus accumulated and unpaid distributions to the date of redemption per Series H preferred unit.

Conversion Rights

The Series H preferred units may be exchanged for common units upon a Series H Change of Control, all on the terms and subject to the conditions and exceptions described in the partnership agreement.

Liquidation Preference

The distribution and income allocation provisions of the partnership agreement have the effect of providing each Series H preferred unit with a liquidation preference equal to $25.00 per unit, plus any accumulated but unpaid distributions, in preference to any other class or series of partnership interest other than those interests expressly designated as ranking on a parity with or senior to the Series H preferred units.

Common Limited Partnership Units

General

The partnership agreement provides that, subject to the distribution preferences of the Series G preferred units and the Series H preferred units and any other preferred units that may be issued in the future, common units are entitled to receive quarterly distributions of available cash on a pro rata basis in accordance with their respective percentage interests. As of September 23, 2016, 2,631,276 issued and outstanding common units were held by our common limited partners other than the Company.

Redemption/Exchange Rights

Common limited partners have the right to require the operating partnership to redeem part or all of their common units for cash based upon the fair market value of an equivalent number of shares of Company common stock at the time of the redemption. Alternatively, the Company may elect to acquire those units tendered for redemption in exchange for shares of Company common stock. The Company’s acquisition will be on a one-for-one basis, subject to adjustment in the event of stock splits, stock dividends, issuance of some rights, some extraordinary distributions and similar events. However, even if the Company elects not to acquire tendered units in exchange for shares of common stock, holders of common units that are corporations or limited liability companies may require that the Company issue common stock in exchange for their common units, subject to applicable ownership limits or any other limit as provided in the Company’s charter or as otherwise determined by the board of directors, as applicable. The Company presently anticipates that the Company will elect to issue

40

shares of common stock in exchange for common units in connection with each redemption request, rather than having the operating partnership redeem the common units for cash. With each redemption or exchange, the Company increases its percentage ownership interest in the operating partnership. Common limited partners may exercise this redemption right from time to time, in whole or in part, except when, as a consequence of shares of common stock being issued, any person’s actual or constructive stock ownership would exceed the ownership limits, or any other limit as provided in the Company’s charter or as otherwise determined by the board of directors.

Common Limited Partner Approval Rights

The partnership agreement provides that if the limited partners own at least 5% of the common units representing common partnership interests in the operating partnership, including those common units held by the Company as general partner, the Company will not, on behalf of the operating partnership and without the prior consent of the holders of more than 50% of the common units representing limited partnership interests in the operating partnership, dissolve the operating partnership, unless the dissolution or sale is incident to a merger or a sale of substantially all of the Company’s assets.

41

CERTAIN PROVISIONS OF MARYLAND LAW AND OF THE COMPANY’S CHARTER AND BYLAWS

The following is a description of certain provisions of Maryland law and the Company’s charter and bylaws. This description is not complete and is subject to, and qualified in its entirety by reference to, Maryland law and the Company’s charter and bylaws. You should read the Company’s charter and bylaws, which are incorporated by reference to our SEC filings. See “Where You Can Find More Information.”

The Board of Directors

The Company’s charter provides that the number of the directors shall be established by its bylaws, but cannot be less than the minimum number required by the Maryland General Corporation Law, or MGCL, which is one. The Company’s bylaws allow the board of directors to fix or change the number to not fewer than three and not more than 13 members. The number of directors is currently fixed at six. A majority of the remaining board of directors may fill any vacancy, other than a vacancy caused by removal. A majority of the board of directors may fill a vacancy resulting from an increase in the number of directors. The stockholders entitled to vote for the election of directors at an annual or special meeting of the Company’s stockholders may fill a vacancy resulting from the removal of a director.

The Company’s charter and bylaws provide that a majority of the board of directors must be “independent directors.” An “independent director” is a director who is not:

No Cumulative Voting

Holders of shares of Company common stock have no right to cumulative voting for the election of directors. Consequently, at each annual meeting of the Company’s stockholders, the holders of a majority of the shares of Company common stock entitled to vote will be able to elect all of the successors of the directors at that meeting.

Removal of Directors

The Company’s charter provides that its stockholders may remove a director only for “cause” and only by the affirmative vote of at least two-thirds of the shares entitled to vote in the election of directors. The MGCL does not define the term “cause.” As a result, removal for “cause” is subject to Maryland common law and to judicial interpretation and review in the context of the unique facts and circumstances of any particular situation.

Election of Directors

The Company’s bylaws provide a majority vote standard for uncontested elections of directors. As a result, except in the case of directors to be elected by the holders of any class or series of the Company’s preferred stock, at each meeting of stockholders at which the election of directors is uncontested, a director nominee will be elected to the board of directors only if the number of votes cast “FOR” the nominee exceeds the number of votes cast “AGAINST” the nominee (with abstentions and broker non-votes not counted as a vote cast either “FOR” or “AGAINST” the director nominee). A plurality vote standard applies in contested elections, in which case stockholders will not be permitted to vote “AGAINST” any director nominee but will only be permitted to vote “FOR” or withhold their vote with respect to such nominee. An election will be considered to be contested if

42

the Company’s secretary has received notice that a stockholder or group of stockholders has nominated or proposes to nominate one or more persons for election as a director and, at least 14 days prior to the date on which notice of the meeting is first mailed to stockholders, the nomination has not been withdrawn and would thereby cause the number of director nominees to exceed the number of directors to be elected at the meeting.

Under the MGCL, if an incumbent director is not re-elected at a meeting of stockholders at which he or she stands for re-election in an uncontested election, then the incumbent director continues to serve in office as a holdover director until his or her successor is elected and qualifies. However, the Company’s bylaws provide that if an incumbent director is not re-elected due to his or her failure to receive a majority of the votes cast in an uncontested election, the director will promptly tender his or her resignation as a director, subject to acceptance by the board of directors. The nominating and corporate governance committee of the board of directors will then make a recommendation to the board of directors as to whether to accept or reject the tendered resignation or whether other action should be taken. The board of directors will publicly disclose within 90 days of certification of the stockholder vote its decision and rationale regarding whether to accept, reject or take other action with respect to the tendered resignation. If a director’s tendered resignation is not accepted by the board of directors, such director would continue to serve until the next annual meeting of stockholders and until his or her successor is elected and qualified or his or her earlier death, retirement, resignation or removal. If a director’s tendered resignation is accepted, then the board of directors may, among other things, fill the resulting vacancy or decrease the size of the board of directors.

The Company is not Subject to the Maryland Business Combination Statute

The Company has elected not to be subject to the “business combination” provisions of the MGCL (sections 3-601 through 3-604) and it cannot rescind such election and become subject to these business combination provisions without the approval of holders of a majority of its shares entitled to vote.

In the event that the Company decides to be subject to the business combinations provision, “business combinations” between a Maryland corporation and an interested stockholder or an affiliate of an interested stockholder are generally prohibited for five years after the most recent date on which the interested stockholder becomes an interested stockholder. A business combination includes a merger, consolidation or share exchange. A business combination may also include an asset transfer or issuance or reclassification of equity securities. An interested stockholder is defined in the MGCL as:

A person is not an interested stockholder under the business combinations provisions of the MGCL if the board of directors approved in advance the transaction by which such person would otherwise have become an interested stockholder.

At the conclusion of the five-year prohibition, any business combination between the Maryland corporation and an interested stockholder generally must be recommended by the board of directors of the corporation and approved by the affirmative vote of at least:

43

These super-majority vote requirements do not apply if the corporation’s common stockholders receive a minimum price, as defined under Maryland law, for their shares in the form of cash or other consideration in the same form as previously paid by the interested stockholder for its shares. None of these provisions of Maryland law will apply, however, to business combinations that are approved or exempted by the board of directors of the corporation prior to the time that the interested stockholder becomes an interested stockholder.

As a result of the Company’s decision not to be subject to the business combinations statute, an interested stockholder would be able to effect a “business combination” without complying with the requirements discussed above, which may make it easier for stockholders who become interested stockholders to consummate a business combination involving the Company. However, the Company cannot assure you that any business combinations will be consummated or, if consummated, will result in a purchase of shares of capital stock from its stockholders at a premium.

The Company is not Subject to the Maryland Control Share Acquisition Statute

The Company has elected in its bylaws not to be subject to the “control share acquisition” provisions of the MGCL (sections 3-701 through 3-710). If it wants to be subject to these provisions, its bylaws would need to be amended. Such amendments would require the approval of the holders of a majority of the shares entitled to vote.

Maryland law provides that “control shares” of a company acquired in a “control share acquisition” have no voting rights except to the extent approved by a vote of two-thirds of the votes entitled to vote, excluding shares owned by the acquiror or by officers or directors who are employees of the Company. “Control shares” are voting shares of stock which, if aggregated with all other voting shares of stock previously acquired by the acquiror, or over which the acquiror is able to directly or indirectly exercise voting power, except solely by revocable proxy, would entitle the acquiror to exercise voting power in electing directors within one of the following ranges of voting power:

“Control shares” do not include shares of stock the acquiring person is entitled to vote having obtained prior stockholder approval. Generally, “control share acquisition” means the acquisition of control shares.

A person who has made or proposes to make a control share acquisition may compel the board of directors to call a special meeting of stockholders to consider voting rights for the shares. The meeting must be held within 50 days of demand. If no request for a meeting is made, the Company may present the question at any stockholders’ meeting.

If voting rights are not approved at the meeting or if the acquiring person does not deliver an acquiring person statement as required by the statute, then, subject to conditions and limitations, the corporation may redeem any or all of the control shares, except those for which voting rights previously have been approved, for fair value. Fair value is determined without regard to the absence of voting rights for control shares, as of the date of the last control share acquisition or of any meeting of stockholders at which the voting rights of control shares are considered and not approved. If voting rights for control shares are approved at a stockholders meeting and the acquiror becomes entitled to vote a majority of the shares entitled to vote, all other stockholders may exercise appraisal rights. The fair value of the shares as determined for purposes of these appraisal rights may not be less than the highest price per share paid in the control share acquisition. Limitations and restrictions otherwise applicable to the exercise of dissenters’ rights do not apply in the context of a control share acquisition.

The control share acquisition statute does not apply to shares acquired in a merger, consolidation or share exchange if the company is a party to the transaction, or to acquisitions approved or exempted by its charter or

44

bylaws. Because the Company is not subject to these provisions, stockholders who acquire a substantial block of Company common stock do not need approval of the other stockholders before exercising full voting rights with respect to their shares on all matters. This may make it easier for any of these control share stockholders to effect a business combination with the Company. However, the Company cannot assure you that any business combinations will be consummated or, if consummated, will result in a purchase of shares of Company common stock from any stockholder at a premium.

Unsolicited Takeovers

Under certain provisions of the MGCL relating to unsolicited takeovers, a Maryland corporation with a class of equity securities registered under the Exchange Act and at least three independent directors may elect to be subject to certain statutory provisions relating to unsolicited takeovers which, among other things, would automatically classify the board of directors into three classes with staggered terms of three years each and vest in its board of directors the exclusive right to determine the number of directors and the exclusive right, by the affirmative vote of a majority of the remaining directors, to fill vacancies on the board of directors, even if the remaining directors do not constitute a quorum. These statutory provisions also provide that any director elected to fill a vacancy shall hold office for the remainder of the full term of the class of directors in which the vacancy occurred, rather than the next annual meeting of directors as would otherwise be the case, and until his successor is elected and qualified.

An election to be subject to any or all of the foregoing statutory provisions may be made in the Company’s charter or bylaws, or by resolution of the board of directors. Any such statutory provision to which the Company elects to be subject will apply even if other provisions of Maryland law or the Company’s charter or bylaws provide to the contrary.

If the Company made an election to be subject to the statutory provisions described above, the board of directors would automatically be classified into three classes with staggered terms of office of three years each, and would have the exclusive right to determine the number of directors and the exclusive right to fill vacancies on the board of directors. Moreover, any director elected to fill a vacancy would hold office for the remainder of the full term of the class of directors in which the vacancy occurred.

In such instance, the classification and staggered terms of office of the directors would make it more difficult for a third party to gain control of the board of directors since at least two annual meetings of stockholders, instead of one, generally would be required to effect a change in the majority of the board of directors.

The Company has not elected to become subject to the foregoing statutory provisions relating to unsolicited takeovers. However, the Company could by resolutions adopted by the board of directors and without stockholder approval, elect to become subject to some or all of these statutory provisions.

Amendment of the Company’s Charter and Bylaws

The Company’s charter may generally be amended only if the amendment is declared advisable by the board of directors and approved by its stockholders by the affirmative vote of at least two-thirds of the shares entitled to vote on the amendment. The Company’s bylaws generally may be amended by the affirmative vote of a majority of the board of directors or of a majority of the Company’s shares entitled to vote. However, the following bylaw provisions may be amended only by the approval of a majority of the Company’s shares of capital stock entitled to vote:

45

Meetings of Stockholders

The Company’s bylaws provide for annual meetings of its stockholders to elect directors and to transact other business properly brought before the meeting. In addition, a special meeting of stockholders may be called by:

The MGCL provides that the Company’s stockholders also may act by unanimous written consent without a meeting with respect to any action that they are required or permitted to take at a meeting. To do so, each stockholder entitled to vote on the matter must sign the consent setting forth the action.

Advance Notice of Director Nominations and New Business

The Company’s bylaws provide that with respect to an annual meeting of stockholders, nominations of persons for election to the board of directors and the proposal of other business to be considered by stockholders at the meeting may be made only:

The Company’s bylaws also provide that with respect to special meetings of stockholders, only the business specified in the notice of meeting may be brought before the meeting.

The advance notice provisions of the Company’s bylaws could have the effect of discouraging a takeover or other transaction in which holders of some, or a majority, of the shares of common stock might receive a premium for their shares over the then prevailing market price or which holders of the Company’s common stock believe is in their best interests.

46

Proxy Access

The Company’s bylaws permit a stockholder, or group of up to ten stockholders, owning at least 5% of the Company’s outstanding common stock continuously for at least the prior three years to nominate a candidate for election to the board of directors and inclusion in the Company’s proxy materials for its annual meeting of stockholders; provided that the total number of all stockholder nominees included in the Company’s proxy materials shall not exceed 25% of the number of directors then serving on the board of directors. The foregoing proxy access right is subject to additional eligibility, procedural and disclosure requirements set forth in the Company’s bylaws.

Exclusive Forum

The Company’s bylaws provide that, unless the Company consents in writing to the selection of an alternative forum, the Circuit Court for Baltimore City, Maryland, or, if that court does not have jurisdiction, the United States District Court for the District of Maryland, Baltimore Division, shall be the sole and exclusive forum for:

Dissolution of the Company

Under the MGCL, the Company may be dissolved if a majority of the entire board of directors determines by resolution that dissolution is advisable and submits a proposal for dissolution for consideration at any annual or special meeting of stockholders, and this proposal is approved, by the vote of the holders of two-thirds of the shares of the Company’s capital stock entitled to vote on the dissolution.

Indemnification and Limitation of Liability of Directors and Officers

The Company’s charter and bylaws, and the partnership agreement, provide for indemnification of its officers and directors against liabilities to the fullest extent permitted by the MGCL, as amended from time to time.

The MGCL permits the Company to indemnify its directors and officers and other parties against judgments, penalties, fines, settlements, and reasonable expenses actually incurred by them in connection with any proceeding to which they may be made a party by reason of their service in those or other capacities unless it is established that:

Under the MGCL, the Company may indemnify its directors or officers against judgments, penalties, fines, settlements and reasonable expenses that they actually incur in connection with the proceeding unless the

47

proceeding is one by the Company or in its right and the director or officer has been found to be liable to the Company. In addition, the Company may not indemnify a director or officer in any proceeding charging improper personal benefit to them if they were found to be liable on the basis that personal benefit was received. The termination of any proceeding by judgment, order or settlement does not create a presumption that the director or officer did not meet the requisite standard of conduct required for indemnification to be permitted. The termination of any proceeding by conviction, or upon a plea of nolo contendere or its equivalent, or an entry of any order of probation prior to judgment, creates a rebuttable presumption that the director or officer did not meet the requisite standard of conduct required for indemnification to be permitted.

In addition, the MGCL provides that, unless limited by its charter, a corporation shall indemnify any director or officer who is made a party to any proceeding by reason of service in that capacity against reasonable expenses incurred by the director or officer in connection with the proceeding, in the event that the director or officer is successful, on the merits or otherwise, in the defense of the proceeding. The Company’s charter contains no such limitation.

As permitted by the MGCL, the Company’s charter limits the liability of its directors and officers to the Company and its stockholders for money damages, subject to specified restrictions. However, the liability of the Company’s directors and officers to it and its stockholders for money damages is not limited if:

This provision does not limit the Company’s ability or its stockholders’ ability to obtain other relief, such as an injunction or rescission.

The partnership agreement provides that the Company, as general partner, and its officers and directors are indemnified to the same extent its officers and directors are indemnified in its charter. The partnership agreement limits the Company’s liability and the liability of its officers and directors to the operating partnership and its partners to the same extent that its charter limits the liability of its officers and directors to it and its stockholders. See “Description of Material Provisions of the Partnership Agreement of Kilroy Realty, L.P.—Indemnification of the Company’s Officers and Directors.”

Insofar as the foregoing provisions permit indemnification of directors, officers or persons controlling the Company for liability arising under the Securities Act of 1933, as amended, the Securities Act, the Company has been informed that in the opinion of the SEC, this indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

Indemnification Agreements

The Company has entered into indemnification agreements with certain of its executive officers and directors. The indemnification agreements provide that:

48

The Company’s indemnification agreements with its executive officers and directors offer substantially the same scope of coverage afforded by applicable law. In addition, as contracts, these indemnification agreements provide greater assurance to its directors and executive officers that indemnification will be available because they cannot be modified unilaterally in the future by the board of directors or the stockholders to eliminate the rights that they provide.

Anti-takeover Effect of Certain Provisions of Maryland Law and of the Company’s Charter and Bylaws

If the resolution of the board of directors exempting the Company from the business combination provisions of the MGCL and the applicable provision in its bylaws exempting it from the control share acquisition provisions of the MGCL are rescinded or revoked (which in each case would require stockholder approval) or it elects to be subject to the unsolicited takeover provisions of the MGCL, then the business combination, control share acquisition and unsolicited takeover provisions of the MGCL, the provisions of its charter on removal of directors, the advance notice provisions of its bylaws and certain other provisions of its charter and bylaws and Maryland law could delay, deter or prevent a change of control of the Company or other transactions that might involve a premium price for holders of its capital stock or otherwise be in their best interest.

49

UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS

The information under this caption “United States Federal Income Tax Considerations” supersedes and replaces in its entirety the information appearing in the Company’s and the operating partnership’s Current Reports on Form 8-K (including the exhibits thereto) filed with the SEC on February 18, 2016 and July 27, 2016. See “Incorporation of Certain Documents by Reference.”

The following is a general summary of certain material United States federal income tax considerations related to the Company’s election to be taxed as REIT and the United States federal income tax considerations anticipated to be material to holders of our capital stock or the operating partnership’s debt securities. This summary is for general information only and is not tax advice. Supplemental United States federal income tax considerations relevant to the ownership of certain securities offered by this prospectus may be provided in the prospectus supplement that relates to those securities. Your tax treatment will vary depending upon the terms of the specific securities you acquire, as well as your particular situation. Unless otherwise expressly stated or the context otherwise requires, all references to “we,” “us” and “our” in this summary refer to the Company.

The information in this summary is based on current law, including:

in each case, as of the date of this summary. These authorities may change or be subject to differing interpretations. The effects of other United States federal tax laws, such as estate and gift tax laws, and any applicable state, local or non-United States tax laws are not discussed. We have not sought and do not plan to seek any rulings from the IRS that we qualify as a REIT or otherwise regarding the matters discussed below. In addition, the administrative interpretations and practices of the IRS include its practices and policies as expressed in private letter rulings that are not binding on the IRS except with respect to the particular taxpayers who requested and received those rulings. The sections of the Code and the corresponding Treasury regulations that relate to qualification and taxation as a REIT are highly technical and complex. The following discussion sets forth certain material aspects of the sections of the Code that govern the United States federal income tax treatment of a REIT and the holders of certain of its securities. This summary is qualified in its entirety by the applicable Code provisions, Treasury regulations promulgated under the Code, and administrative and judicial interpretations thereof. Future legislation, Treasury regulations, administrative interpretations and practices and/or court decisions may adversely affect the tax considerations contained in this discussion. Any such change could apply retroactively in a manner that could adversely affect a holder of our capital stock or the operating partnership’s debt securities. Thus, we can provide no assurance that the tax considerations contained in this summary will not be challenged by the IRS or will be sustained by a court if so challenged.

You are urged to consult your tax advisor regarding the tax consequences to you of:

50

Taxation of the Company

General. We elected to be taxed as a REIT under Sections 856 through 860 of the Code, commencing with our taxable year ended December 31, 1997. We believe that we have been organized and have operated in a manner that has allowed us to qualify for taxation as a REIT under the Code commencing with our taxable year ended December 31, 1997, and we intend to continue to be organized and operate in this manner. However, qualification and taxation as a REIT depend upon our ability to meet the various qualification tests imposed under the Code, including through actual annual operating results, asset composition, distribution levels and diversity of stock ownership. Accordingly, no assurance can be given that we have been organized and have operated, or will continue to be organized and operate, in a manner so as to qualify or remain qualified as a REIT. See “—Failure to Qualify.”

Latham & Watkins LLP has rendered an opinion to us to the effect that, commencing with our taxable year ended December 31, 1997, we have been organized and have operated in conformity with the requirements for qualification and taxation as a REIT, and that our proposed method of operation will enable us to continue to meet the requirements for qualification and taxation as a REIT, under the Code. It must be emphasized that this opinion was based on various assumptions and representations as to factual matters, including representations made by us in a factual certificate provided by one of our officers. In addition, this opinion was based upon our factual representations set forth in this prospectus concerning our business, assets and governing documents, as well as the business, assets and governing documents of the operating partnership and our other subsidiaries. Moreover, our qualification and taxation as a REIT depend upon our ability to meet the various qualification tests imposed under the Code which are discussed in more detail below, including through actual annual operating results, asset composition, distribution levels and diversity of stock ownership, the results of which have not been and will not be reviewed by Latham & Watkins LLP. Accordingly, no assurance can be given that our actual results of operation for any particular taxable year have satisfied or will satisfy those requirements. See “—Failure to Qualify” below. Further, the United States federal income tax consequences related to the acquisition, ownership and disposition of our capital stock described below may be changed, perhaps retroactively, by legislative, administrative or judicial action at any time. Latham & Watkins LLP has no obligation to update its opinion subsequent to its date.

Provided we qualify for taxation as a REIT, we generally will not be required to pay United States federal corporate income taxes on our net income that is currently distributed to our stockholders. This treatment substantially eliminates the “double taxation” that ordinarily results from investment in a C corporation. A C corporation is a corporation that generally is required to pay tax at the corporate-level. Double taxation means taxation once at the corporate level when income is earned and once again at the stockholder level when the income is distributed. We will, however, be required to pay United States federal income tax as follows:

51

Requirements for Qualification as a Real Estate Investment Trust. The Code defines a REIT as a corporation, trust or association:

52

The Code provides that conditions (1) to (4), inclusive, must be met during the entire taxable year and that condition (5) must be met during at least 335 days of a taxable year of twelve months, or during a proportionate part of a taxable year of less than twelve months. Conditions (5) and (6) do not apply until after the first taxable year for which an election is made to be taxed as a REIT. For purposes of condition (6), the term “individual” includes a supplemental unemployment compensation benefit plan, a private foundation or a portion of a trust permanently set aside or used exclusively for charitable purposes, but generally does not include a qualified pension plan or profit sharing trust.

We believe that we have been organized, have operated and have issued sufficient shares of capital stock with sufficient diversity of ownership to allow us to satisfy conditions (1) through (7) inclusive, during the relevant time periods. In addition, our charter with respect to our common stock, and the articles supplementary with respect to preferred stock we may issue from time to time, provide for restrictions regarding the ownership and transfer of our shares which are intended to assist us in continuing to satisfy the share ownership requirements described in conditions (5) and (6) above. These stock ownership and transfer restrictions with respect to our common stock are described in Article IV of our charter. These restrictions, however, do not ensure that we have previously satisfied, and may not ensure that we will, in all cases, be able to continue to satisfy the share ownership requirements described in conditions (5) and (6) above. If we fail to satisfy these share ownership requirements, except as provided in the next sentence, our status as a REIT will terminate. If, however, we comply with the rules contained in applicable Treasury regulations that require us to ascertain the actual ownership of our shares and we do not know, or would not have known through the exercise of reasonable diligence, that we failed to meet the requirement described in condition (6) above, we will be treated as having met this requirement. See “—Failure to Qualify.”

In addition, we may not maintain our status as a REIT unless our taxable year is the calendar year. We have and will continue to have a calendar taxable year.

Ownership of Interests in Partnerships, Limited Liability Companies and Qualified REIT Subsidiaries. We own and operate one or more properties through partnerships and limited liability companies. Treasury regulations generally provide that, in the case of a REIT that is a partner in a partnership or a member in a limited liability company treated as a partnership for United States federal income tax purposes, the REIT will be deemed to own its proportionate share of the assets of the partnership or limited liability company, as the case may be, based on its interest in partnership capital, subject to special rules relating to the 10% asset test described below. Also, pursuant to Treasury regulations, the REIT will be deemed to be entitled to its proportionate share of the income of that entity. The assets and gross income of the partnership or limited liability company retain the same character in the hands of the REIT, including for purposes of satisfying the gross income tests and the asset tests. Thus, our pro rata share of the assets and items of income of the operating partnership, including the operating partnership’s share of these items of any partnership or limited liability company treated as a partnership or disregarded entity for United States federal income tax purposes in which it owns an interest is treated as our assets and items of income for purposes of applying the requirements described in this discussion, including the gross income and asset tests described below. A brief summary of the rules governing the United States federal income taxation of partnerships and limited liability companies below in “—Tax Aspects of the Operating Partnership, the Subsidiary Partnerships and Limited Liability Companies.”

53

We have direct control of the operating partnership and certain subsidiary partnerships and limited liability companies and we intend to continue to operate them in a manner consistent with the requirements for our qualification as a REIT. From time to time, we may be a limited partner or non-managing member in certain partnerships and limited liability companies. If any such partnership or limited liability company were to take actions that could jeopardize our status as a REIT or require us to pay tax, we could be forced to dispose of our interest in such entity. In addition, it is possible that a partnership or limited liability company could take an action which could cause us to fail a REIT income or asset test, and that we would not become aware of such action in time to dispose of our interest in the partnership or limited liability company or take other corrective action on a timely basis. In that case, we could fail to qualify as a REIT unless we were entitled to relief, as described below. See “—Failure to Qualify” below.

We may from time to time own and operate certain properties through wholly-owned subsidiaries that we intend to be treated as “qualified REIT subsidiaries” under the Code. A corporation will qualify as our qualified REIT subsidiary if we own 100% of the corporation’s outstanding stock and we do not elect with the corporation to treat it as a “taxable REIT subsidiary,” as described below. A qualified REIT subsidiary is not treated as a separate corporation, and all assets, liabilities and items of income, gain, loss, deduction and credit of our qualified REIT subsidiaries will be treated as our assets, liabilities and such items, for all purposes of the Code, including the REIT qualification tests. Thus, in applying the United States federal tax requirements described in this prospectus, any corporations in which we own a 100% interest (other than any taxable REIT subsidiaries) are ignored, and all assets, liabilities and items of income, gain, loss, deduction and credit of such corporations are treated as our assets, liabilities, and items of income, gain, loss, deduction and credit. A qualified REIT subsidiary is not required to pay United States federal income tax, and our ownership of the stock of a qualified REIT subsidiary does not violate the restrictions on ownership of securities, as described below under “—Asset Tests.”

Ownership of Interests in Taxable REIT Subsidiaries. A taxable REIT subsidiary of ours is a corporation other than a REIT in which we directly or indirectly hold stock and that has made a joint election with us to be treated as a taxable REIT subsidiary. A taxable REIT subsidiary also includes any corporation other than a REIT with respect to which a taxable REIT subsidiary owns securities possessing more than 35% of the total voting power or value of the outstanding securities of such corporation. Other than some activities relating to lodging and health care facilities, a taxable REIT subsidiary may generally engage in any business, including the provision of customary or non-customary services to tenants of its parent REIT. A taxable REIT subsidiary is subject to income tax as a regular C corporation. In addition, a taxable REIT subsidiary of ours may be prevented from deducting interest on debt that we directly or indirectly fund if certain tests regarding the taxable REIT subsidiary’s debt-to-equity ratio and interest expense are satisfied. Our ownership of securities of our taxable REIT subsidiaries will not be subject to the 10% or 5% asset tests described below. See “—Asset Tests.” We currently own interests in Kilroy Realty TRS, Inc., and we have jointly elected with Kilroy Realty TRS, Inc. to have it be treated as a taxable REIT subsidiary. We may acquire interests in additional taxable REIT subsidiaries in the future.

Income Tests. We must satisfy two gross income requirements annually to maintain our qualification as a REIT. First, in each taxable year we must derive directly or indirectly at least 75% of our gross income, excluding gross income from prohibited transactions, certain hedging transactions, and certain foreign currency gains, from investments relating to real property or mortgages on real property, including “rents from real property,” dividends from other REITs and, in certain circumstances, interest on obligations adequately secured by mortgages on real property, or certain types of temporary investments. Second, in each taxable year we must derive at least 95% of our gross income, excluding gross income from prohibited transactions, certain hedging transactions, and certain foreign currency gains, from the real property investments described above or dividends, interest and gain from the sale or disposition of stock or securities, or from any combination of the foregoing.

For these purposes, the term “interest” generally does not include any amount received or accrued, directly or indirectly, if the determination of all or some of the amount depends in any way on the income or profits of

54

any person. However, an amount received or accrued generally will not be excluded from the term “interest” solely by reason of being based on a fixed percentage or percentages of receipts or sales.

Rents we receive from a tenant will qualify as “rents from real property” for the purpose of satisfying the gross income requirements for a REIT described above only if all of the following conditions are met:

We generally do not intend, and as a general partner of the operating partnership do not intend to permit the operating partnership, to take actions we believe will cause us to fail to satisfy the rental conditions described above. However, we may intentionally fail to satisfy some of these conditions to the extent such failure will not, based on the advice of our tax counsel, jeopardize our tax status as a REIT. In addition, with respect to the limitation on the rental of personal property, we have not obtained appraisals of the real property and personal property leased to tenants. Accordingly, there can be no assurance that the IRS will agree with our determinations of value.

Income we receive that is attributable to the rental of parking spaces at the properties will constitute rents from real property for purposes of the REIT gross income tests if certain services provided with respect to the parking facilities are performed by independent contractors from whom we derive no income, either directly or

55

indirectly, or by a taxable REIT subsidiary, and certain other conditions are met. We believe that the income we receive that is attributable to parking facilities meets these tests and, accordingly, will constitute rents from real property for purposes of the REIT gross income tests.

From time to time, we may enter into hedging transactions with respect to one or more of our assets or liabilities. The term “hedging transaction” generally means (A) any transaction we enter into in the normal course of our business primarily to manage risk of (1) interest rate changes or fluctuations with respect to borrowings made or to be made by us to acquire or carry real estate assets, or (2) currency fluctuations with respect to an item of qualifying income under the 75% or 95% gross income test and (B) for taxable years beginning after December 31, 2015, new hedging transactions entered into to hedge the income or loss from prior hedging transactions, where the property or indebtedness which was the subject of the prior hedging transaction was extinguished or disposed of. The hedging activities may include entering into interest rate swaps, caps, and floors, options to purchase these items, and futures and forward contracts. Income we derive from a hedging transaction, including gain from the sale or disposition thereof, that is clearly identified as a hedging transaction as specified in the Code will not constitute gross income and thus will be exempt from the 95% and 75% gross income tests.

To the extent that we do not properly identify such transactions as hedges or we hedge with other types of financial instruments, the income from those transactions is not likely to be treated as qualifying income for purposes of the gross income tests. We intend to structure any hedging transactions in a manner that does not jeopardize our status as a REIT.

To the extent our taxable REIT subsidiary, Kilroy Realty TRS, Inc., pays dividends, we generally will derive our allocable share of such dividend income through our interest in the operating partnership. Such dividend income will qualify under the 95%, but not the 75%, REIT gross income test.

We will monitor the amount of the dividend and other income from our taxable REIT subsidiaries and will take actions intended to keep this income, and any other nonqualifying income, within the limitations of the REIT income tests. While we expect these actions will prevent a violation of the REIT income tests, we cannot guarantee that such actions will in all cases prevent such a violation. If we fail to satisfy one or both of the 75% or 95% gross income tests for any taxable year, we may nevertheless qualify as a REIT for the year if we are entitled to relief under certain provisions of the Code. We generally may avail ourselves of the relief provisions if:

It is not possible, however, to state whether in all circumstances we would be entitled to the benefit of these relief provisions. For example, if we fail to satisfy the gross income tests because nonqualifying income that we intentionally accrue or receive exceeds the limits on nonqualifying income, the IRS could conclude that our failure to satisfy the tests was not due to reasonable cause. If these relief provisions do not apply to a particular set of circumstances, we will not qualify as a REIT. As discussed above in “—Taxation of the Company—General,” even if these relief provisions apply, and we retain our status as a REIT, a tax would be imposed with respect to our nonqualifying income. We may not always be able to comply with the gross income tests for REIT qualification despite periodic monitoring of our income.

Prohibited Transaction Income. Any gain that we realize on the sale or other disposition of property held as inventory or otherwise held primarily for sale to customers in the ordinary course of business, including our share of any such gain realized by the operating partnership, either directly or through its subsidiary partnerships

56

and limited liability companies, will be treated as income from a prohibited transaction that is subject to a 100% penalty tax, unless certain safe harbor exceptions apply. This prohibited transaction income may also adversely affect our ability to satisfy the income tests for qualification as a REIT. Under existing law, whether property is held as inventory or primarily for sale to customers in the ordinary course of a trade or business is a question of fact that depends on all the facts and circumstances surrounding the particular transaction. We intend to hold our properties for investment with a view to long-term appreciation, to engage in the business of acquiring, developing and owning properties and to make occasional sales of the properties consistent with our investment objectives. We do not intend, and do not intend to permit the operating partnership or its subsidiary partnerships or limited liability companies, to enter into any sales that are prohibited transactions. However, the IRS may successfully contend that some or all of the sales made by us or by the operating partnership or its subsidiary partnerships or limited liability companies are prohibited transactions. We would be required to pay the 100% penalty tax on our allocable share of the gains from any such sales.

Penalty Tax. Any redetermined rents, redetermined deductions, excess interest or (for taxable years beginning after December 31, 2015) redetermined taxable REIT subsidiary service income we generate will be subject to a 100% penalty tax. In general, redetermined rents are rents from real property that are overstated as a result of any services furnished to any of our tenants by one of our taxable REIT subsidiaries, and redetermined deductions and excess interest represent any amounts that are deducted by a taxable REIT subsidiary for amounts paid to us that are in excess of the amounts that would have been deducted based on arm’s length negotiations and redetermined taxable REIT subsidiary service income is income of a taxable REIT subsidiary that is understated as a result of services provided to us or on our behalf. Rents we receive will not constitute redetermined rents if they qualify for certain safe harbor provisions contained in the Code.

We believe that, in all instances in which Kilroy Realty TRS, Inc. provides services to our tenants, the fees paid to Kilroy Realty TRS, Inc. for such services are at arm’s-length rates, although the fees paid may not satisfy the safe-harbor provisions contained in the Code. These determinations are inherently factual, and the IRS has broad discretion to assert that amounts paid between related parties should be reallocated to clearly reflect their respective incomes. If the IRS successfully made such an assertion, we would be required to pay a 100% penalty tax on the excess of an arm’s-length fee for tenant services over the amount actually paid.

Asset Tests. At the close of each quarter of our taxable year, we must also satisfy certain tests relating to the nature and diversification of our assets.

First, at least 75% of the value of our total assets, including assets held by our qualified REIT subsidiaries and our allocable share of the assets held by the operating partnership and its subsidiary partnerships and other entities treated as partnerships for United States federal income tax purposes, must be represented by real estate assets, cash, cash items and government securities. For purposes of this test, the term “real estate assets” generally means real property (including interests in real property and interests in mortgages on real property) and shares (or transferable certificates of beneficial interest) in other REITs, as well as any stock or debt instrument attributable to investment of the proceeds of a stock offering or a public offering of debt with a term of at least five years, but only for the one-year period beginning on the date we receive such proceeds. For taxable years beginning after December 31, 2015, the term “real estate assets” also includes debt instruments of publicly offered REITs, personal property securing a mortgage secured by both real property and personal property if the fair market value of such personal property does not exceed 15% of the total fair market value of all such property, and personal property leased in connection with a lease of real property for which the rent attributable to personal property is not greater than 15% of the total rent received under the lease.

Second, not more than 25% of the value of our total assets may be represented by securities (including securities of taxable REIT subsidiaries), other than those securities includable in the 75% asset test.

Third, of the investments included in the 25% asset class, and except for investments in other REITs, our qualified REIT subsidiaries and our taxable REIT subsidiaries, the value of any one issuer’s securities may not

57

exceed 5% of the value of our total assets and we may not own more than 10% of the total vote or value of the outstanding securities of any one issuer, except, in the case of the 10% value test, securities satisfying the “straight debt” safe-harbor or securities issued by a partnership that itself would satisfy the 75% income test if it were a REIT. Certain types of securities we may own are disregarded as securities solely for purposes of the 10% value test, including but not limited to, any loan to an individual or an estate, any obligation to pay rents from real property and any security issued by a REIT. In addition, solely for purposes of the 10% value test, the determination of our interest in the assets of a partnership or limited liability company in which we own an interest will be based on our proportionate interest in any securities issued by the partnership or limited liability company, excluding for this purpose, certain securities described in the Code.

Fourth, not more than 25% (20% for taxable years beginning after December 31, 2017) of the value of our total assets may be represented by the securities of one or more taxable REIT subsidiaries. The operating partnership owns 100% of the outstanding stock of Kilroy Realty TRS, Inc. Kilroy Realty TRS, Inc. elected, together with us, to be treated as a taxable REIT subsidiary. So long as Kilroy Realty TRS, Inc. qualifies as our taxable REIT subsidiary, we will not be subject to the 5% asset test, the 10% voting securities limitation or the 10% value limitation with respect to our ownership of securities in Kilroy Realty TRS, Inc. We or Kilroy Realty TRS, Inc. may acquire securities in other taxable REIT subsidiaries in the future. We believe that the aggregate value of our taxable REIT subsidiaries has not exceeded, and in the future will not exceed 25% (or 20% for taxable years beginning after December 31, 2017) of the aggregate value of our gross assets. With respect to each issuer in which we currently own an interest that does not qualify as a REIT, a qualified REIT subsidiary or a taxable REIT subsidiary, we believe that our ownership of the securities of any such issuer has complied with the 5% asset test, the 10% voting securities limitation, 10% value limitation, and the 75% asset test. We generally do not obtain independent appraisals to support these conclusions. In addition, there can be no assurance that the IRS will not disagree with our determinations of value.

Fifth, for taxable years beginning after December 31, 2015, not more than 25% of the value of our total assets may be represented by debt instruments of publicly offered REITs to the extent those debt instruments would not be real estate assets but for the inclusion of debt instruments of publicly offered REITs in the meaning of real estate assets effective for taxable years beginning after December 31, 2015, as described above.

The asset tests described above must be satisfied at the close of each calendar quarter of our taxable year in which we (directly or through the operating partnership or our subsidiary partnerships and limited liability companies) acquire securities in the applicable issuer, and also at the close of each calendar quarter in which we increase our ownership of securities of such issuer (including as a result of increasing our interest in the operating partnership or in our subsidiary partnerships and limited liability companies). For example, our indirect ownership of securities of each issuer will increase as a result of our capital contributions to the operating partnership and as limited partners exercise their redemption/exchange rights. After initially meeting the asset tests at the close of any quarter, we will not lose our status as a REIT for failure to satisfy the asset tests at the end of a later quarter solely by reason of changes in asset values. If we fail to satisfy an asset test because we acquire securities or other property during a quarter (including as a result of an increase in our interests in the operating partnership or in our subsidiary partnerships and limited liability companies), we may cure this failure by disposing of sufficient nonqualifying assets within 30 days after the close of that quarter. We believe that we have maintained and intend to maintain adequate records of the value of our assets to ensure compliance with the asset tests. In addition, we intend to take such actions within 30 days after the close of any quarter as may be required to cure any noncompliance.

Certain relief provisions may be available to us if we fail to satisfy the asset tests described above after the 30 day cure period. Under these provisions, we will be deemed to have met the 5% and 10% asset tests if the value of our nonqualifying assets (i) does not exceed the lesser of (a) 1% of the total value of our assets at the end of the applicable quarter or (b) $10,000,000, and (ii) we dispose of the nonqualifying assets or otherwise satisfy such asset tests within (a) six months after the last day of the quarter in which the failure to satisfy the asset tests is discovered or (b) the period of time prescribed by Treasury regulations to be issued. For violations

58

of any of the asset tests due to reasonable cause and not due to willful neglect and that are, in the case of the 5% and 10% asset test, in excess of the de minimis exception described above, we may avoid disqualification as a REIT, after the 30 day cure period, by taking steps including (i) the disposition of sufficient nonqualifying assets, or the taking of other actions, which allow us to meet the asset tests within (a) six months after the last day of the quarter in which the failure to satisfy the asset tests is discovered or (b) the period of time prescribed by Treasury regulations to be issued, and (ii) disclosing certain information to the IRS. In such case, we will be required to pay a tax equal to the greater of (a) $50,000 or (b) the highest corporate tax rate multiplied by the net income generated by the nonqualifying assets.

Although we believe that we have satisfied the asset tests described above and plan to take steps to ensure that we satisfy such tests for any quarter with respect to which retesting is to occur, there can be no assurance that we will always be successful, or will not require a reduction in the operating partnership’s overall interest in an issuer (including in a taxable REIT subsidiary). If we fail to cure any noncompliance with the asset tests in a timely manner, and the relief provisions described above are not available, we would cease to qualify as a REIT. See “—Failure to Qualify” below.

Annual Distribution Requirements. To maintain our qualification as a REIT, we are required to distribute dividends, other than capital gain dividends, to our stockholders in an amount at least equal to the sum of:

For these purposes, our “real estate investment trust taxable income” is computed without regard to the dividends paid deduction and our net capital gain. In addition, for purposes of this test, non-cash income generally means income attributable to leveled stepped rents, original issue discount, cancellation of indebtedness or a like-kind exchange that is later determined to be taxable.

Also, our “REIT taxable income” will be reduced by any taxes we are required to pay on any gain we recognize from the disposition of any asset we acquired from a corporation that is or has been a C corporation in a transaction in which our basis in the asset is less than the fair market value of the asset, in each case determined at the time we acquired the asset, within a specified period beginning on the date on which we acquired such asset. See “—General” above.

We generally must pay, or be treated as paying, the distributions described above in the taxable year to which they relate. At our election, a distribution for a taxable year may be declared before we timely file our tax return for such year and paid on or before the first regular dividend payment after such declaration, provided such payment is made during the twelve-month period following the close of such year. These distributions generally are taxable to our stockholders, other than tax-exempt entities, in the year in which paid. This is so even though these distributions relate to the prior year for purposes of the 90% distribution requirement. In order to be taken into account for purposes of our distribution requirement, unless (for distributions made in taxable years beginning after December 31, 2014) we qualify as a “publicly offered REIT,” the amount distributed must not be preferential (i.e., every stockholder of the class of stock to which a distribution is made must be treated the same as every other stockholder of that class, and no class of stock may be treated other than in according to its dividend rights as a class). We believe that we are, and expect we will continue to be, a “publicly offered REIT.” To the extent that we do not distribute all of our net capital gain or distribute at least 90%, but less than 100%, of our “real estate investment trust taxable income,” as adjusted, we will be required to pay tax on the undistributed amount at regular corporate tax rates. We believe we have made, and intend to continue to make, timely distributions sufficient to satisfy these annual distribution requirements and to minimize our corporate tax obligations. In this regard, the partnership agreement of the operating partnership authorizes us, as general partner of the operating partnership, to take such steps as may be necessary to cause the operating partnership to distribute to its partners an amount sufficient to permit us to meet these distribution requirements.

59

We expect that our real estate investment trust taxable income will be less than our cash flow because of depreciation and other non-cash charges included in computing real estate investment trust taxable income. Accordingly, we anticipate that we generally will have sufficient cash or liquid assets to enable us to satisfy the distribution requirements described above. However, from time to time, we may not have sufficient cash or other liquid assets to meet these distribution requirements due to timing differences between the actual receipt of income and actual payment of deductible expenses, and the inclusion of income and deduction of expenses in arriving at our taxable income. If these timing differences occur, we may be required to borrow funds to pay cash dividends or to pay dividends in the form of taxable stock dividends in order to meet the distribution requirements, while preserving our cash. In addition, we may decide to retain our cash, rather than distribute it, in order to repay debt or for other reasons.

Under some circumstances, we may be able to rectify an inadvertent failure to meet the 90% distribution requirement for a year by paying “deficiency dividends” to our stockholders in a later year, which may be included in our deduction for dividends paid for the earlier year. Thus, we may be able to avoid being taxed on amounts distributed as deficiency dividends, subject to the 4% excise tax described below. However, we will be required to pay interest to the IRS based upon the amount of any deduction claimed for deficiency dividends. While the payment of a deficiency dividend will apply to a prior year for purposes of our REIT distribution requirements, it will be treated as an additional distribution to our stockholders in the year such dividend is paid.

Furthermore, we will be required to pay a 4% excise tax to the extent we fail to distribute during each calendar year, at least the sum of 85% of our real estate investment trust ordinary income for such year, 95% of our real estate investment trust capital gain net income for the year and any undistributed taxable income from prior periods. Any real estate investment trust ordinary income and net capital gain on which this excise tax is imposed for any year is treated as an amount distributed during that year for purposes of calculating such tax.

For purposes of the 90% distribution requirement and excise tax described above, dividends declared during the last three months of the taxable year, payable to stockholders of record on a specified date during such period, and paid during January of the following year, will be treated as paid by us and received by our stockholders on December 31 of the year in which they are declared.

Like-Kind Exchanges. We have in the past disposed of properties in transactions intended to qualify as like-kind exchanges under the Code, and may continue this practice in the future. Such like-kind exchanges are intended to result in the deferral of gain for United States federal income tax purposes. The failure of any such transaction to qualify as a like-kind exchange could subject us to United States federal income tax, possibly including the 100% prohibited transaction tax, depending on the facts and circumstances surrounding the particular transaction.

Tax Liabilities and Attributes Inherited in Connection with Acquisitions. We have, and may in the future, acquire other corporations or entities and, in connection with such acquisitions, we may succeed to the historic tax attributes and liabilities of such entities. For example, if we acquire a C corporation and subsequently dispose of its assets within a specified period beginning on the date on which we acquired such assets, we could be required to pay the built-in gain tax described above under “—General.” In addition, in order to qualify as a REIT, at the end of any taxable year, we must not have any earnings and profits accumulated in a non-REIT year. As a result, if we acquire a C corporation, we must distribute the corporation’s earnings and profits accumulated prior to the acquisition before the end of the taxable year in which we acquire the corporation. We also could be required to pay the acquired entity’s unpaid taxes even though such liabilities arose prior to the time we acquired the entity.

Failure to Qualify

Specified cure provisions are available to us in the event that we discover a violation of a provision of the Code that would result in our failure to qualify as a REIT. Except with respect to violations of the REIT income

60

tests and asset tests (for which the cure provisions are described above), and provided the violation is due to reasonable cause and not due to willful neglect, these cure provisions generally impose a $50,000 penalty for each violation in lieu of a loss of REIT status.

If we fail to qualify for taxation as a REIT in any taxable year, and the relief provisions do not apply, we will be required to pay tax, including any applicable alternative minimum tax, on our taxable income at regular corporate rates. Distributions to stockholders in any year in which we fail to qualify as a REIT will not be deductible by us, and we will not be required to distribute any amounts to our stockholders. As a result, we anticipate that our failure to qualify as a REIT would reduce the cash available for distribution by us to our stockholders. In addition, if we fail to qualify as a REIT, all distributions to stockholders will be taxable as regular corporate dividends to the extent of our current and accumulated earnings and profits. In this event, corporate distributees may be eligible for the dividends-received deduction. In addition, non-corporate stockholders, including individuals may be eligible for the preferential tax rates on qualified dividend income. Unless entitled to relief under specific statutory provisions, we would also be ineligible to elect to be treated as a REIT for the four taxable years following the year during which we lost our qualification. It is not possible to state whether in all circumstances we would be entitled to this statutory relief.

Interests in Subsidiary REITs

We have acquired, and may acquire in the future, interests in subsidiary REITs. Provided that our subsidiary REITs qualify as REITs for United States federal income tax purposes, our interests in such subsidiary REITs will be treated as qualifying real estate assets for purposes of the REIT asset tests and any dividend income or gains derived by us from such subsidiary REITs will generally be treated as income that qualifies for purposes of the REIT gross income tests. To qualify as a REIT, a subsidiary REIT must independently satisfy the various REIT qualification requirements described in this summary. If a subsidiary REIT of ours were to fail to qualify as a REIT, and the relief provisions described in this summary do not apply, it would be treated as a regular taxable corporation and its income would be subject to United States federal income tax. In addition, shares in such subsidiary REIT would cease to be qualifying assets for purposes of the asset tests applicable to REITs, and our income from such shares would cease to qualify under the REIT 75% gross income test. As a result, a failure of a subsidiary REIT of ours to qualify as a REIT would have an adverse effect on our ability to comply with the REIT asset and income tests, and would prevent us from qualifying as a REIT, unless we could avail ourselves of such relief provisions.

Tax Aspects of the Operating Partnership, the Subsidiary Partnerships and Limited Liability Companies

General. Substantially all of our investments are held indirectly through the operating partnership. In addition, the operating partnership holds certain of its investments indirectly through subsidiary partnerships and limited liability companies which we believe are and will continue to be treated as partnerships or disregarded entities for United States federal income tax purposes. In general, entities that are treated as partnerships (or disregarded entities) for United States federal income tax purposes are “pass-through” entities which are not required to pay United States federal income tax. Rather, partners or members of such entities are allocated their shares of the items of income, gain, loss, deduction and credit of the entity, and are potentially required to pay tax on this income, without regard to whether the partners or members receive a distribution of cash from the entity. We will include in our income our proportionate share of the foregoing items for purposes of the various REIT income tests and in the computation of our real estate investment trust taxable income. Moreover, as described above under “—Asset Tests,” for purposes of the asset tests, we will generally include our proportionate share of assets held by the operating partnership, including its share of assets held by its subsidiary partnerships and limited liability companies, based on our capital interests. See “—Taxation of the Company.”

Entity Classification. Our interests in the operating partnership and its subsidiary partnerships and limited liability companies involve special tax considerations, including the possibility that the IRS might challenge the status of any of these entities as a partnership (or disregarded entity). For example, an entity that would otherwise

61

be treated as a partnership for United States federal income tax purposes may nonetheless be taxable as a corporation if it is a “publicly traded partnership” and certain other requirements are met. A partnership or limited liability company would be treated as a publicly traded partnership if its interests are traded on an established securities market or are readily tradable on a secondary market or a substantial equivalent thereof, within the meaning of applicable Treasury regulations. We do not anticipate that the operating partnership or any subsidiary partnership or limited liability company will be treated as a publicly traded partnership that is taxable as a corporation. However, if any such entity were treated as a corporation, it would be required to pay an entity-level tax on its income. In this situation, the character of our assets and items of gross income would change and could prevent us from satisfying the asset tests and possibly the income tests (see “—Taxation of the Company—Asset Tests” and “—Income Tests”). This, in turn, could prevent us from qualifying as a REIT. See “—Failure to Qualify” for a discussion of the effect of our failure to meet these tests for a taxable year. In addition, a change in the operating partnership’s, a subsidiary partnership’s or a subsidiary limited liability company’s status for tax purposes might be treated as a taxable event. If so, we might incur a tax liability without any related cash distributions. The Company believes the operating partnership and each of its other partnerships and limited liability companies are and will continue to be treated as partnerships or disregarded entities for United States federal income tax purposes.

Allocations of Income, Gain, Loss and Deduction. A partnership or limited liability company agreement will generally determine the allocation of income and loss among partners or members. These allocations, however, will be disregarded for tax purposes if they do not comply with the provisions of Section 704(b) of the Code and the related Treasury regulations. Generally, Section 704(b) of the Code and the related Treasury regulations require that partnership and limited liability company allocations respect the economic arrangement of the partners or members.

The partnership agreement of the operating partnership provides for preferred distributions of cash and preferred allocations of income to the holders of its preferred units. Preferred units have been issued to us in connection with our issuance of preferred stock. Upon our issuance of additional shares of preferred stock for cash or other consideration, we will contribute the net proceeds or other consideration from such issuance to the operating partnership in exchange for additional preferred units with similar terms. In general, all remaining items of income and loss will be allocated to the holders of common units in proportion to the number of common units held by each unit holder. See the discussion under “Description of Material Provisions of the Partnership Agreement of Kilroy Realty, L.P.—Allocations of Net Income and Net Losses to Partners” included elsewhere in this prospectus, describing the allocations of net income and net losses to partners required pursuant to the partnership agreement of the operating partnership. Some limited partners have agreed to guarantee debt of the operating partnership, either directly or indirectly through an agreement to make capital contributions to the operating partnership under limited circumstances. As a result, and notwithstanding the above discussion of allocations of income and loss to holders of common units, these limited partners could under limited circumstances be allocated a disproportionate amount of net loss of the operating partnership or a disproportionate amount of net income of the operating partnership to offset any such allocations of net loss.

If an allocation is not recognized by the IRS for United States federal income tax purposes, the item subject to the allocation will be reallocated in accordance with the partners’ or members’ interests in the partnership or limited liability company. This reallocation will be determined by taking into account all of the facts and circumstances relating to the economic arrangement of the partners or members with respect to such item. The operating partnership’s allocations of taxable income and loss are intended to comply with the requirements of Section 704(b) of the Code and the Treasury regulations promulgated thereunder.

Tax Allocations with Respect to the Properties. Under Section 704(c) of the Code, income, gain, loss and deduction attributable to appreciated or depreciated property that is contributed to a partnership or limited liability company treated as a partnership for United States federal income tax purposes in exchange for an interest in the partnership or limited liability company, must be allocated in a manner so that the contributing partner or member is charged with the unrealized gain, or benefits from the unrealized loss, associated with the

62

property at the time of the contribution, as adjusted from time to time. The amount of the unrealized gain or unrealized loss generally is equal to the difference between the fair market value or book value and the adjusted tax basis of the property at the time of contribution. These allocations are solely for United States federal income tax purposes and do not affect the book capital accounts or other economic or legal arrangements among the partners or members. The operating partnership was formed by way of contributions of appreciated property (i.e., property having an adjusted tax basis less than its fair market value at the time of contribution). Moreover, subsequent to the formation of the operating partnership, additional appreciated property has been contributed to the operating partnership in exchange for interests in the operating partnership. The partnership agreement requires that these allocations be made in a manner consistent with Section 704(c) of the Code.

Treasury regulations issued under Section 704(c) of the Code provide partnerships and limited liability companies treated as partnerships for United States federal income tax purposes with a choice of several methods of accounting for book-tax differences, including retention of the “traditional method” or the election of certain methods which would permit any distortions caused by a book-tax difference to be entirely rectified on an annual basis or with respect to a specific taxable transaction such as a sale. We and the operating partnership have determined to use the “traditional method” for accounting for book-tax differences for the properties initially contributed to the operating partnership and for certain assets contributed subsequently. We and the operating partnership have not yet decided what method will be used to account for book-tax differences for properties acquired by the operating partnership in the future.

In general, the partners of the operating partnership who acquired their limited partnership interests through a contribution of appreciated property will be allocated depreciation deductions for tax purposes that are lower than such deductions would have been if they had been determined on a pro rata basis. In addition, in the event of the disposition of any of the contributed assets which have such a book-tax difference, all income attributable to such book-tax difference (as adjusted) generally will be allocated to the contributing partners. These allocations will tend to eliminate the book-tax difference over the life of the operating partnership. However, under the traditional method, the special allocation rules of Section 704(c) of the Code do not always entirely eliminate the book-tax difference on an annual basis or with respect to a specific taxable transaction such as a sale. Thus, the carryover basis of the contributed assets in the hands of the operating partnership may cause us or other partners to be allocated lower depreciation and other deductions, and possibly an amount of taxable income in the event of a sale of such contributed assets in excess of the economic or book income allocated to us or other partners as a result of the sale. Such an allocation might cause us or other partners to recognize taxable income in excess of cash proceeds, which might adversely affect our ability to comply with the REIT distribution requirements. See “—Taxation of the Company—Requirements for Qualification as a Real Estate Investment Trust” and “—Annual Distribution Requirements.”

Any property acquired by the operating partnership in a taxable transaction will initially have a tax basis equal to its fair market value, and Section 704(c) of the Code will not apply.

Partnership Audit Rules. The Bipartisan Budget Act of 2015 changes the rules applicable to United States federal income tax audits of partnerships. Under the new rules (which generally are effective for taxable years beginning after December 31, 2017), among other changes and subject to certain exceptions, any audit adjustment to items of income, gain, loss, deduction, or credit of a partnership (and any partner’s distributive share thereof) is determined, and taxes, interest, or penalties attributable thereto are assessed and collected, at the partnership level. Although it is uncertain how these new rules will be implemented, it is possible that they could result in partnerships in which we directly or indirectly invest being required to pay additional taxes, interest and penalties as a result of an audit adjustment, and we, as a direct or indirect partner of these partnerships, could be required to bear the economic burden of those taxes, interest, and penalties even though we, as a REIT, may not otherwise have been required to pay additional corporate-level taxes as a result of the related audit adjustment. The changes created by these new rules are sweeping and in many respects dependent on the promulgation of future regulations or other guidance by the United States Department of the Treasury. Prospective investors are urged to consult their tax advisors with respect to these changes and their potential impact on their investment in our shares.

63

Material United States Federal Income Tax Consequences for Holders of Our Capital Stock and the Operating Partnership’s Debt Securities

The following discussion is a summary of certain United States federal income tax consequences to you of acquiring, owning and disposing of our capital stock or the operating partnership’s debt securities. This discussion is limited to holders who hold our capital stock or the operating partnership’s debt securities as “capital assets” within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion does not address all of the United States federal income tax consequences relevant to a holder’s particular circumstances, including the impact of the tax on net investment income imposed by Section 1411 of the Code. In addition, except where specifically noted, it does not address consequences relevant to holders subject to particular rules, including, without limitation: