Castonzo’s deal is for $43.6 million over four years, reports NFL.com’s Ian Rapoport. It will pay him $35 million over the first three seasons.
Castonzo was chosen by the Colts in the first round of the 2011 NFL draft and has started all 60 games he’s played in Indianapolis.
The four-year veteran played all 1,400 snaps last season for Indianapolis, including the playoffs.
The Colts visit the Bills at 1 p.m. ET Sunday to begin their 2015 campaign.
- Kenny Ducey