Cliff Byrne, United's captain, has signed a two-year contract extension. The Irishman, 28, has made 294 appearances since joining the club from Sunderland in 2003.
"I've had a good conversation with the chairman and I'm happy we've sorted it," he told United's official website.
"We've spoken about the deal in bits and pieces over the last six months, but I prefer to just put it to bed now the season is finished and everyone knows where we are."