Villanueva has been placed on the Ravens' reserve/retirement list, Clifton Brown of the team's official site reports.
The two-time Pro Bowler spent the first six years of his NFL career with the Steelers before his lone season with the Ravens in 2021. Villanueva's retirement should clear $6 million in salary cap space for Baltimore ahead of NFL free agency, while the team hopes that left tackle Ronnie Stanley -- who Villanueva filled in for last year -- will be back in 2022 to reclaim his starting role along the team's offensive line.