Kate Middleton paid homage to her husband on Father's Day with a message on social media.

The Princess of Wales shared a photo Sunday of Prince William with his back turned. 

Beside him, also facing away from the camera, were the couple's three children — Prince George, Princess Charlotte and Prince Louis. William had his arms around his children as they gazed out at the ocean from the sand.

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"We love you, Papa. Happy Father’s Day," the caption said, with the children's initials, "G, C & L."

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Father's Day falls on the third Sunday of June in both the United States and the United Kingdom. Earlier in the day, William shared his own Father's Day tribute to his dad, King Charles.

William shared a throwback image of himself as a child with a younger Charles on the official Instagram account for the Prince and Princess of Wales.

"Happy Father’s Day, Pa. W," he captioned the image.

The Father's Day posts come just a day after Middleton made her first public appearance in months to attend the Trooping the Colour event.

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On Friday, Kate released a statement on social media, telling followers, "I am making good progress, but as anyone going through chemotherapy will know, there are good days and bad days. On those bad days you feel weak, tired and you have to give in to your body resting. But on the good days, when you feel stronger, you want to make the most of feeling well.

"My treatment is ongoing and will be for a few more months. On the days I feel well enough, it is a joy to engage with school life, spend personal time on the things that give me energy and positivity, as well as starting to do a little work from home."

The princess acknowledged she is "not out of the woods yet" but said she was "looking forward" to Saturday's event. She also said she hopes to attend "a few public engagements over the summer."

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"I am learning how to be patient, especially with uncertainty," she said. "Taking each day as it comes, listening to my body, and allowing myself to take this much needed time to heal."

Trooping the Colour takes place in June each year to celebrate the monarch’s birthday, regardless of when the monarch's actual birthday is. The annual event highlights the ceremonial presentation of the military’s flags or "colours."

Middleton was photographed riding in a carriage to the event. Later, she was spotted on the balcony of the palace, posing for photos with Prince William, children Prince Louis, Prince George and Princess Charlotte and King Charles and Queen Camilla.

Fox News Digital's Emily Trainham contributed to this report