Fua, a third-round pick by the Panthers in 2011, was among the final roster cuts on Aug. 31. The past two years he played in 24 games with 12 starts.
He will add depth to an already solid defensive front that held the Seattle Seahawks to 70 yards rushing in a 12-7 loss on Sunday.
Carolina also signed offensive lineman Mike Jasper to the practice squad and re-signed defensive tackle Casey Walker to the practice squad. Walker also was among the team's final cuts.