The Longsight-born player, who is now tied to United until June 2012, has made the right-back spot his own this season in the absence of injured captain Gary Neville.
The former Red Devils trainee said in a statement: "Manchester United is a fantastic club and I am delighted to have signed a new deal.
"To be part of a team I have supported all my life is a great honour.
"I can see this team winning many trophies in the coming seasons and it will be great to share in that success."
Manager Sir Alex Ferguson, who criticised Brown's agent earlier in the season when it appeared he may end his 12-year stay at Old Trafford, praised the defender's contribution to the side.
"I am delighted Wes has signed a new contract, he has grown up at this club and is an integral part of the squad," said Ferguson.
"He has done a great job during Gary's absence and has been a major factor in our outstanding defensive performance."