The deal is worth $6.55 million with $2.6 million guaranteed, a league source confirmed to ESPNChicago.com.
Garza was in the final year of a six-year deal he inked in January 2006.
An 11-year NFL veteran and team captain, Garza, 32, started 85 games at guard for the Bears before moving to center at the start of training camp after the club failed to come to terms with Olin Kreutz. Garza is credited with bringing stability to an offensive line that's undergone significant changes the past two seasons.
The offensive line didn't surrender a sack in the Bears' 30-24 victory over Philadelphia, the first time quarterback Jay Cutler finished a game without being taken down in almost two years.
Garza was a fourth-round selection by Atlanta in the 2001 NFL Draft and arrived in Chicago during the 2005 season.
Michael C. Wright covers the Bears for ESPNChicago.com and ESPN 1000.