Forte sprained the medial collateral ligament in his right knee early in a loss to Kansas City on Dec. 4 and sat out the rest of the season.
Forte came into last season looking for an extension, but did not reach an agreement with the Bears.
Forte was reportedly offered a deal that guaranteed about $13 million or $14 million, but might have been looking for something closer to the five-year, $43 million contract with $21 million guaranteed that Carolina gave DeAngelo Williams.
"Matt is an important part of our football team and we chose to utilize the franchise tag to ensure he remains a Bear," Bears general manager Phil Emery said. "We believe in Matt as a player and a person. Our intention is to continue to work to find common ground and keep Matt as a member of the Chicago Bears in 2012 and beyond."