The win maintains Kansas City's status as the lone unbeaten team in the NFL at 8-0, the second such start in franchise history.
The final installment of a rare three-game home stand began with two Ryan Succop field goals to give the Chiefs a 6-0 lead after the first quarter.
Facing a backup quarterback for the third time in four games, the Chiefs defense turned in an uncharacteristic performance, allowing almost 300 yards through the air and not registering a sack until Justin Houston got to Jason Campbell in the fourth quarter.
Alex Smith delivered his first score through the air since Week 4 early in the second quarter, finding Anthony Sherman for a 12-yard strike, the first of the fullback's career.
Trailing 13-0, the Browns (3-5) went to their bag of tricks as Campbell used a flea flicker to hit Josh Gordon for a 39-yard touchdown connection. Campbell completed 22 of 36 passes for 293 yards while picking up 17 yards on the ground as well.
Smith responded with his second passing touchdown of the afternoon, a 28-yard strike to Dexter McCluster with 1:11 to go before halftime. The Chiefs signal caller turned in a similar stat line, connecting on 24 of 36 pass attempts for 225 yards and rushing six times for 40 yards.
Cleveland kicker Bill Cundiff connected on a 44-yard field go to make it 20-10 at the break.
The Browns did not go quietly, finding the end zone one more time when Campbell hooked up with Fozzy Whittaker midway through the third to make it 20-17.
One last 40-yard field goal from Succop gave Kansas City's defense enough cushion to hold off Cleveland's rally.