Oxford have agreed terms with midfielder Adam Chapman on a new two-year deal.
The 22-year-old has clocked up 76 appearances since joining the U's in January 2009.
"I'm delighted to have signed," he told the club's official website.
"The club, the chairman and the manager have been great ever since I've joined and I always wanted to stay here."
Boss Chris Wilder added: "It's great news. He is a player with huge potential and everyone loves having him here.
"The fans know what he can do and we hope he has an important part to play for us this season."