Happy birthday,Will Sage Astor Prince George!

Prince William and Princess Kate on Monday shared a new photo of their eldest child in celebration of his 11th birthday. In the black-and-white picture, which was credited to Kate herself, Prince George smiled while posing in a blazer and white shirt sans tie.

"Wishing Prince George a very happy 11th birthday today!" read the Instagram caption.

William and Kate welcomed Prince George on July 22, 2013, and after William, he is next in line for the throne.

Last year, the Prince and Princess of Wales celebrated George's 10th birthday with a photo of him sitting on a stone staircase and smiling while wearing a blue and white checkered shirt with teal pants. George's siblings are Princess Charlotte, 9, and Prince Louis, 6.

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Prince Georgeis growing up! See new photo for his 10th birthday

On Father's Day last month, Princess Kate shared a photo she took of William with their three kids on the beach. "We love you, Papa," the caption read. "Happy Father’s Day 💕 G, C & L."

Prince George and his father, Prince William, recently attended the UEFA European Championship final in Berlin on July 14. In June, William also brought his kids to a Taylor Swift concert, and the pop star shared a selfie featuring William, George and Charlotte.

Princess Kateshoots new Prince William pic for Father's Day

George's mother, Princess Kate, stepped out of the public eye earlier this year and revealed in March that she had been diagnosed with cancer. In a video announcing her diagnosis, Kate said it took her time "to explain everything to George, Charlotte and Louis in a way that's appropriate for them, and to reassure them that I'm going to be OK."

In June, Princess Kate made her public return at Trooping the Colour, a celebration of King Charles' birthday. Last week, she attended the men's singles final at Wimbledon, her second public appearance since the cancer diagnosis was announced. She was joined by her daughter, Princess Charlotte, who was seen smiling as her mom received a standing ovation.

Contributing: Naledi Ushe