The royal posted the touching tribute on Instagram where she shared a new family photo of her and Jack holding hands with their one-year-old son August.
The post read: “What a birthday to celebrate in the park with my boys. Thank you Xx”.
She included a ‘kissing emoji’ in the touching caption.
British journalist and writer, Omid Scobie, who also co-wrote the book Finding Freedom, posted the image and Eugenie’s caption on his Twitter account.
It comes as the princess turned 32 on Wednesday and celebrated the occasion with family and friends.
The princess’ post caused a frenzy of heartfelt comments with royal fans extending their well wishes to the family.
One user, veronicayvonnesalasramiro, commented: “Beautiful picture in you Birthday God Bless you for you and family”.
carilgastwirth also wrote: “The happiest of birthdays to you Princess Eugenie. You have so much support and loved by many”.
Another praised the “sweet” family picture.
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The royal was born in 1990, two years after her older sister Princess Beatrice and is one of the Queen and the late Duke of Edinburgh’s grandchildren.
She is currently twelfth in line to the throne.
Eugenie and husband Jack Brooksbank’s only child, August, turned one on February 9
The pair married in October 2018 at Windsor Castle, after meeting eight years earlier while both skiing in Switzerland.