Welch, 27, now becomes an unrestricted free agent and is free to sign with any team.
The 6-foot-7, 310-pound lineman served as a backup swing tackle for the Bills last season. He was one of their top reserve linemen last season, but the Bills could be looking to upgrade at the position this offseason.
Welch could still return to the team at a reduced cost. In order to retain his rights as a restricted free agent, the Bills would have needed to tender Welch a deal worth at least $1.3 million.