Saints assistant head coach Joe Vitt says the restricted free agent signed the tender from New Orleans on Tuesday. The Saints had offered Casillas a little less than $1.3 million for next season and would have lost him without compensation if they had failed to match a higher offer from another club.
Casillas played in 13 games last season, starting four, and was credited with 57 total tackles, three sacks and three passes defended.
Casillas is entering his fourth season out of Wisconsin. He missed the entire 2010 regular season with a foot injury.