"I am so happy to become patron of Horatio's Garden. @horatiosgarden creates beautiful, and completely accessible, gardens for all patients at spinal injury centres across the UK," Eugenie wrote in the caption.
"Since learning about this charity back in 2016, I have fallen in love with their mission to bring joy to people and help their recovery.
"In 2017 I was able to visit Horatio’s Garden in Scotland, and in March this year I saw the site that has been identified at the Royal National Orthopaedic Hospital, where I underwent spinal surgery.
"As a former spinal patient myself, I understand how the chance to get outside is so beneficial not only for recovery, but for staying positive at a life-changing, and often traumatic, time. I hope to learn from the patients I meet and the wonderful people working to create these gardens. #garden 🌹🌳🍄"
Horatio's Garden responded by thanking the Princess, declaring they are "so very grateful for your patronage".
The Princess famously underwent surgery for scoliosis when she was just 12-years-old.
Eugenie made a bold statement on her royal wedding day to Jack Brooksbank in October 2018 by choosing a custom Peter Pilotto gown which showed off the surgical scar on her back.
Fans were delighted to see the young royal engage with the charity, with one writing: "I had scoliosis when I was 14 and totally understand the pain you have to go through. Thank you for helping create beautiful gardens for patients."
Another user dismissed the two Princesses of York's joint reputations for being somewhat work shy, saying: "I think you should be acknowledged as a working member [of the royal family]. You do a lot."
And Eugenie may well be preparing for an even busier schedule, as royal fans are convinced the newlywed is expecting her first child.
WATCH this video to see 'Eug' describe her close bond with sister Beatrice!