Willis and the Niners agreed to a five-year contract extension Tuesday that takes him through the 2016 season. This is another big offseason splash by new San Francisco personnel chief Trent Baalke, who took charge after general manager Scot McCloughan's abrupt departure in March.
Locking up Willis for the long haul makes sure the 49ers keep their defensive leader after they bolstered their offense in the draft with two top linemen.
The 25-year-old Willis, the 49ers' 11th overall pick in the first round of the 2007 NFL draft, has led the team in tackles in each of his first three seasons and has made 48 straight starts. He's the first 49er since Ronnie Lott to have made it to the Pro Bowl in each of his first three seasons.
Willis hasn't missed a game in his NFL career.