The Colts (3-3) already have won one more game than they did in 2011.
Brandon Weeden threw for 247 yards and two touchdowns, but Trent Richardson, who tried to play through a rib cartilage injury, sat out the second half after running eight times for 8 yards in the first half. The Browns (1-6) have lost 11 consecutive road games.
Luck scored on runs of 3 and 5 yards in the first half.
Adam Vinatieri added a 38-yard field goal for Indianapolis.
Copyright 2012 by The Associated Press