The appearance comes just before the couple head out for their tour of Germany and Poland, which kicks off - with the kids! - on Monday.
The newlyweds still had their honeymoon glow as they cheered on American tennis star Sam Querrey and Marin Cilic of Croatia.
In a new documentary about the United Kingdom tennis tournament, Kate described watching Wimbledon from courtside as "amazing". "Sadly, never the same results".
In the documentary, Kate also recalled a starstruck moment involving her dad, Michael Middleton, and tennis champ Pete Sampras.
Kate said: 'Congratulations. Very, very well played, honestly, it was fantastic. "My father is not going to enjoy this, but we were walking past Tim Henman. My dad said very cooly, 'Hi, Pete.' I said, 'Dad, you can't do that!' I was mortified".