The Bills announced the deal on Friday, a little over a week after 2006 NFL rookie of the year worked out for the team at its facility.
General manager Buddy Nix said the addition of Young will create more competition at the backup spot behind starter Ryan Fitzpatrick.
Young, who turns 29 later this month, has been biding his time to determine the next step of his career after he completed his one-year contract with the Philadelphia Eagles last season. He struggled as Michael Vick‘s backup last season, finishing with four touchdowns and nine interceptions in six games, including three starts.