Belgium international Mignolet has earned a number of plaudits for his performances between the posts for the Black Cats this season.
"I've been so fortunate throughout my career to play alongside some top keepers," he told the club's official website. "I've played with Brad and Joe and they're great – Simon is in the same category.
"People say that Joe is the best keeper in the world; I think that Simon's definitely up there with the best and I'm sure other people will agree."
Mignolet, 24, joined Sunderland in 2010 from Saint-Truiden.