The Chiefs (8-0), off to their best start since 2003, built a 20-7 lead late in the first half before the Browns (3-4) made it a game.
Jason Campbell, starting in place of the ineffective Brandon Weeden, threw for 293 yards and two touchdowns for the Browns.
The second scoring pass, a 17-yarder to Fozzy Whittaker out of the backfield, got Cleveland within a field goal early in the third quarter.
The Chiefs kept stopping the Browns down the stretch, though. They forced a turnover on downs with just over 2 minutes left, and Ryan Succop kicked his third field goal in the closing seconds to help seal the victory.