They also released rookie tight end Zach Sudfeld after he struggled following an impressive preseason.
Wilfork tore his right Achilles tendon in the first quarter of Sunday night's 30-23 win over the Atlanta Falcons. The five-time Pro Bowl player has missed just six games in his 10-year career.
Collie spent his four pro seasons with the Indianapolis Colts, but played in just one game last year because of a knee injury. He signed with San Francisco as a free agent Aug. 2 and was released Aug. 31. In 42 games, he has 173 catches for 1,845 yards and 16 touchdowns. He brings experience to a wide receiver group that includes three rookies, but also has a history of concussions.