The princess, wearing a green dress to match the green grass of the All England Club, was accompanied by her husband, Prince William, and their two oldest children, Prince George and Princess Charlotte.
Prince William, who was wearing a gray blazer, is the heir to the British throne.
The royal family was in the Royal Box for the men's final between seven-time champion Novak Djokovic and Carlos Alcaraz, with Kate set to present the trophy to the winner.
King Felipe VI of Spain was also in the Royal Box to watch as Alcaraz becomes the third Spanish player to play in the men's final at Wimbledon.
Several former Wimbledon champions were also invited, including Billie Jean King, Chris Evert, Stan Smith, Stefan Edberg and Jan Kodes.
The ambassadors from Serbia and Spain were also scheduled to be there.
Princess Kate is the patron of the All England Club and has been in the Royal Box a few times already this year, sitting next to eight-time champion Roger Federer one day and next to King — Billie Jean King, that is — on Saturday for the women's final.