Chicago racked up 20 points off the turnovers.
Forte scored on runs of 1 and 10 yards, ending up with 90 yards rushing.
Chicago quarterback Jay Cutler was 17-of-30 passing for 225 yards.
Quarterback Derek Anderson ran 1 yard for Cleveland's touchdown. Anderson finished with six completions for 76 yards and two interceptions.
The Browns are 1-7.