The Princess completed the challenge in aid of the hospital where she was treated for cancer.
The photographs show Middleton with her children Prince George, Princess Charlotte and Prince Louis, and her husband the Prince of Wales after climbing Yr Wyddfa (Snowdon) in north Wales last week.
Credit: Instagram @princeandprincessofwales
The Princess revealed that she was receiving cancer treatment in 2024 and later said she was in remission at the start of 2025.
She posted the photos to Instagram on Sunday, the caption read: "This time last week, completing the National Three Peaks Challenge. A huge thank you to everybody who has supported The Royal Marsden Cancer Charity. To find out more or donate, please visit link in bio 🔗."
In the photos, Middleton was also joined by her parents Carole and Michael Middleton and her brother James.
Credit: Instagram @princeandprincessofwales
Her brother also posted to social media, sharing photos after the his sister's challenge.
He wrote on Instagram that he was "incredibly proud" of his sister.
"Two years ago, I told you we’d climb this mountain together. We talked about climbing mountains while you were in hospital, and about the incredible healing power that nature can have for both the body and the mind. So it was such an honour to join you for your Three Peaks Challenge for the Royal Marsden Cancer Charity," his caption read.
"Seeing how far you’ve come is nothing short of inspiring. Your strength, resilience, and determination, all while being the most amazing mother, wife, daughter, and sister, inspire me and so many others every single day. Keep being exactly who you are ✨ If you’d like to support or learn more about the Royal Marsden Cancer Charity, please visit the link in my bio," the post continued.
After the challenge, the Princess said she aimed to raise awareness for the "deeper impact of serious illness and the importance of holistic healthcare."
"Every individual is different, and ensuring there is a whole person approach to care enables those living through cancer to manage the deeply personal challenge of diagnosis," she said according to the BBC.
