The statue was unveiled at an intimate ceremony in Kensington Gardens with only 13 guests alongside the brothers, including the late royal's siblings.
WATCH: Prince William and Prince Harry put on a united front at unveiling of Princess Diana statue
The stunning artwork, cast in bronze, shows the statue surrounded by three children and depicts Diana in the later years of her life.
Beneath the statue is a plinth engraved with the Princess' name and the date of the unveiling, while a paving stone in front is engraved with an extract after the poem The Measure of A Man, which was in the programme for the 2007 memorial service for the Princess.
Fans all noted how "beautiful" the statue was
Royal fans adored the incredible tribute, and when the official Instagram account for the Duke and Duchess of Cambridge posted a picture from the event, they rushed to say how "beautiful" the piece was.
One fan said: "Great photo. Wonderful to see the brothers unveiling together. Amazing statue."
A second commented: " Beautiful tribute, may she Rest In Peace & continue to inspire generations to come," and a third added: "Absolutely wonderful, what a fitting tribute for a beautiful woman."
The royal brothers also paid a sweet tribute to their late mother in a joint statement.
The royal brothers released an emotional statement
They said: "Today, on what would have been our mother's 60th birthday, we remember her love, strength and character – qualities that made her a force for good around the world, changing countless lives for the better.
"Every day, we wish she were still with us, and our hope is that this statue will be seen forever as a symbol of her life and her legacy.
"Thank you to Ian Rank-Broadley, Pip Morrison and their teams for their outstanding work, to the friends and donors who helped make this happen, and to all those around the world who keep our mother’s memory alive."
Make sure you never miss a ROYAL story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.