Brown joins Black Cats
The 31-year-old England international has joined the Black Cats for an undisclosed fee, understood to be in the region of £1million.
Sunderland had a joint bid of more than £12million for Brown, John O'Shea and Darron Gibson accepted last month, and Republic of Ireland defender O'Shea was also on Wearside on Thursday for a medical.
Manager Steve Bruce said: "We are delighted to welcome a player of Wes' ability, experience and character to the club.
"He has been a fantastic professional for Manchester United through the years and not only will he strengthen our defensive options, he will also bring with him a winning mentality and level of maturity which can only be positive for the players around him."
Brown is Bruce's seventh summer signing after Ahmed Elmohamady, Connor Wickham, Craig Gardner, Ji Dong-won, Keiren Westwood and Sebastian Larsson, and is unlikely to be the last with O'Shea and Blackpool midfielder David Vaughan also understood to be close to agreeing deals.
The defender made senior 361 appearances for United over 15 years as a professional having joining the club as a 12-year-old, and has five Premier League winners' medals.
Brown won 23 England caps before announcing his retirement from the international game last summer.
He will bring a welcome versatility and vast experience to the Stadium of Light, where his arrival will go some of the way to making up for the loss of loan signings Nedum Onuoha and John Mensah.
Ostensibly a central defender, he can also play at right-back and with O'Shea equally comfortable across the back four as well as in midfield, Bruce could have healthy options at the back next season.
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