The 33-year-old was out of contract after being released by Sheffield United and joins Chris Wilder's men on a two-year deal.
Kitson told the the U's official website: "I had a number of clubs interested but the ambition and the set-up here at Oxford is excellent and there is a buzz about the club at the moment.
"It is a good club with a good manager and a very good squad. Oxford is the only League Two club that I considered because at this stage in my career I am looking to be part of a successful promotion campaign.
"I am looking forward to joining up with them for pre-season, working hard, and playing my part in what I am sure will be a very exciting few years for the club."
Manager Chris Wilder added: "Dave has a proven stature and has scored goals at the top level. He is very experienced and he makes goals for other people too.
"As soon as we knew he was available he was my number one target for the summer. He had options in higher divisions but I think it speaks volumes for Oxford United and the way we do things here that he wanted to come and play for us."