The deal gives Whitehair the second-largest guarantee for a guard extension in NFL history.
Finalizing a lucrative extension for Whitehair was a preseason priority for the Bears. Chicago previously locked up starting left tackle Charles Leno to a four-year extension that contained $18 million in guarantees. Starting right tackle Bobby Massie re-signed in the offseason for four years and $15.8 million guaranteed.
Selected by the Bears in the second round of the 2016 NFL draft, Whitehair has started every game since his rookie year and has played three different positions (center, left guard, right guard).
Whitehair started 16 games at center last year, but moved to left guard in the offseason.
"Obviously Cody is an important player for us," Bears general manager Ryan Pace said in July. "When we talk about our culture and we talk about unselfish and great teammates, Cody embodies all those things."
Whitehair suffered a minor finger injury during camp but will be ready for Chicago's Week 1 opener on Thursday night against Green Bay.