Details of the deal were not disclosed. It runs through the 2012 season.
Vasher has 16 interceptions in his first three N-F-L seasons.
He was chosen in the fourth round out of Texas in 2004 and has blossomed into one of the team's top defenders, making the Pro Bowl last season.
In 2005 he set an N-F-L record for the longest play when he returned a missed field goal 108 yards for a touchdown against the 49ers, a play that was matched in distance last season by teammate Devin Hester.
Vasher was originally signed through 2007.
He says it feels good to have a new contract and that it's one less thing he has to worry about.