Carson Palmer went 12-for-15 for 105 yards while Dave Rayner connected on 4- of-5 field goal tries for the Bengals, who dropped their preseason opener against Dallas. Bernard Scott had 65 yards on eight carries while Jordan Shipley had five catches for 50 yards.
Kyle Orton finished 8-for-13 for 84 yards and tossed touchdowns to Eddie Royal and Brandon Lloyd for the Broncos, who were making their preseason debut and finished last season with a mark of 8-8, second place in the AFC West.
Heisman Trophy winner Tim Tebow made his NFL debut and went 8-for-13 for 105 yards and ran the ball into the end zone from seven yards out on the final play of the game.
The Broncos held a 14-0 lead after the first quarter as Orton tossed touchdown passes of 12 yards to Royal and six yards to Lloyd.
Benson punched the ball into the end zone from a yard out, Rayner kicked a 36- yard field goal and David Jones returned an interception 24 yards to give the Bengals a 17-14 lead in the second quarter.
Matt Prater, though, booted a 28-yard field goal to tie the game going into halftime.
Field goals of 27 and 31 yards off the foot of Rayner in the third quarter gave Cincinnati a 23-17 lead.
The Bengals continued to pour it on in the fourth as Johnson scored from a yard out and Rayner punched a 26-yard field goal for a 33-17 advantage.