Flynn was cut Monday, three weeks after the Bills signed the sixth-year player. The Bills were in need of experienced depth with Manuel sidelined by a sprained right knee.
Manuel has been cleared for practice after missing four games. He could return as early as Sunday, when Buffalo (3-6) travels to Pittsburgh (2-6).
Buffalo filled the open roster spot by signing fullback Evan Rodriguez. Selected in the fourth round of the 2012 draft by Chicago, he had four catches for 21 yards in 12 games last season. Rodriguez was waived by the Bears in June after being charged with driving under the influence, his second alcohol-related arrest.