To make room for Nwaneri, the team placed guard Tyronne Green (calf strain) on the reserve/injured list.
Nwaneri, a 2007 fifth-round draft pick by Jacksonville, started in 92 of 104 games in his career.
The Garland, Texas native, played high school football at Naaman Forest High School.
Nwaneri adds depth to the offensive line that's in need of youth and experience. Currently, there is only one spot open along the line, at left guard, and the Cowboys are having Ronald Leary and Mackenzy Bernadeau compete for that spot.