Cincinnati also placed defensive tackle Adolphus Washington on injured reserve in a corresponding transaction. The Bengals announced the roster moves on Friday.
Ringo, 26, was a sixth-round pick by the Green Bay Packers in the 2015 NFL Draft. The Louisiana-Lafayette product was with the Packers through the 2016 season before spending time with the Bengals and Detroit Lions last season. He was inactive for one game for the Bengals in 2017 before being waived. Ringo spent time on the Cowboys' roster and practice squad this season and played in one game.
For his career, the 6-foot-1, 298-pound defensive lineman has five tackles and a forced fumble in 15 games.
Washington was a third-round pick by the Buffalo Bills in the 2016 NFL Draft. The 6-foot-4, 295-pound defensive lineman signed with the Bengals off the Cowboys' practice squad on Sept. 26. Washington, an Ohio State product, suffered a knee injury in the Bengals' Nov. 11 loss to the New Orleans Saints. He logged six tackles and a sack in four games this season for the Bengals.
Washington was listed as a backup to Pro Bowl defensive tackle Geno Atkins on the Bengals' depth chart before the injury.