Jones was on the reserve/injured designated to return list since Oct. 18 with a groin injury. Jones hasn't played in a game since Sept. 29 at San Diego where he finished with two tackles and one quarterback pressure.
He was inactive the next two weeks before the Cowboys moved him to the injured list.
Lemon was signed off the Arizona Cardinals practice squad on Nov. 21 and played in just two games. Lemon was inactive for Dallas' game at Chicago on Monday night.
Adding Jones to the active roster gives the Cowboys 11 defensive linemen.