Formerly, listing a player on injured reserve made him ineligible for the remainder of the season but the NFL altered the rule allowing for a return to game action after eight weeks. McGahee would be able to play in the AFC Championship game if Denver advances that far in the playoffs.
McGahee, 31, suffered a torn medial collateral ligament in his right knee Sunday. The team said McGahee won't need surgery to repair the injury, shortening his recovery time.
McGahee is fifth in rushing in the AFC with 731 yards on 167 carries and four touchdowns. He's caught 26 passes for 221 yards. Last year he ran for 1,199 yards, a career best.
Rookie Ronnie Hillman and Lance Ball are expected to split McGahee's playing time at running back.
The Broncos, who lead the AFC West with a 7-3 record, play Sunday at 1-9 Kansas City.