The stunning royal wore a gorgeous crisp white blazer from Zara with her hair in her signature long waves and could be seen cheering on the English team from the stands, along with many other fans.
Keep reading to see some of Kate's best moments at the nail-biting event...
WATCH: Princess Kate reveals sporting regret in surprise royal chat
Kate's arrival
The Princess wore a stunning white blazer and dark trousers for her arrival at the match between England and Fiji, which was held at the Stade Velodrome in Marseille.
Kate, who is a huge fan of rugby, has been attending more events without her husband and seeming ever more confident in her royal role since becoming Princess of Wales.
The mum-of-three appeared to be sharing her insights into the game with her seatmates as England played Fiji, and the latter team started to fight back.
While supporting her local team, the generous-hearted royal always recognises both sides' efforts in high-quality international matches, and being so athletic herself, understands the hard work it takes to succeed.
The Prince and Princess of Wales moved to Forest Lodge on the Windsor Home Park estate with Prince George, Princess Charlotte, and Prince Louis in November 2025
The Princess of Wales and Princess Charlotte surprised many with a joint piano recital – and the pair's bond was praised by a composer who worked with them