Taking to her Instagram page, the daughter of Prince Andrew and Sarah Ferguson shared a throwback image with her grandmother from Trooping the Colour in 1998.
WATCH: The Queen's Jubilee through the years
The snap saw Eugenie standing next to the Queen and the late Duke of Edinburgh as they watched the traditional fly-past from the balcony of Buckingham Palace.
In the caption, the 32-year-old remarked: "Happy 96th Birthday Granny! You have been such an inspiration to me and so many across the world. Thank you for your support, love and strength. Xx."
The post comes shortly after Eugenie's cousin, the Duke of Cambridge and his wife Kate, sent their well wishes. The royal couple selected two touching photos to accompany their message, the first of which showed William and Kate with the monarch as they showed her round the Duchess's Back to Nature Garden at the 2019 Chelsea Flower Show.
Princess Eugenie uploaded this throwback snap with the Queen
The second image poignantly shows the Queen and her late husband Prince Philip posing with seven of their great-grandchildren.
"Wishing Her Majesty The Queen a very happy 96th birthday today!" William and Kate wrote in the caption. "An inspiration to so many across the UK, the Commonwealth and the world, it's particularly special to be celebrating in this #PlatinumJubilee year."
In celebration of the Queen's birthday, a new photo has been released by the Palace, showing the monarch enjoying the spring sunshine as she holds the reins of two of her beloved ponies.
On Wednesday, she was flown by helicopter to Sandringham where she is marking her milestone birthday in private. The Queen is staying at Wood Farm, the modest cottage which the Duke of Edinburgh made his retirement base in his final years. The royal couple spent many happy weekends there together over the years and the Queen will no doubt spend time reflecting on treasured memories.
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