In the video, William, 40, with Princess Charlotte on his lap, praising the Lionesses for making it to the finals, before finishing the video, Charlotte says “good luck and I hope you win” as she waves at the camera.
In a social media post, the royal added: “Good luck tonight Lionesses, we’re all cheering for you!”
England will take on eight-time champions Germany later on Sunday in a bid to pick up their first major trophy in women’s game history.
On Sunday, the Lionesses will look for revenge against Germany after a 6-2 defeat in the European Championship final of 2009.
Before the match, Boris Johnson and Sir Keir Starmer also paid tribute to the team.
The Prime Minister said: “Your passion for the game, your tenacity in tricky spots and most importantly your amazing talent on the pitch have already provided millions of us with a summer full of fantastic memories.
“You can see it in the sold-out stadiums, in the overcrowded fan zones, in the little kids dancing wildly to Sweet Caroline and the TV ratings that have seen records crumble almost as completely as the Swedish defense in the semi-finals. ”
Johnson added: “In every pride it is the lionesses who hunt relentlessly as a team and take home their prize, and I’m sure that will be the case against Germany.”
Sir Keir added: “As a parent I know how important it is to see strong, successful role models in sport. What you and your team achieved this summer will be celebrated not only as a great moment for English football, but also as one that has encouraged and inspired young women like my own daughter.”
He added: “It’s coming home!”
England defeated Sweden 4-0 in the semi-final at Bramall Lane on Tuesday and will try to break the odds against a team that has won 21 of their 27 encounters.