Trindon Holliday also returned a kickoff a Broncos-record 105 yards for a touchdown.
Manning improved to 8-0 career against Cincinnati (3-5), which has lost four in a row for the first time in two years. This win didn't come so easily.
The four-time MVP threw a pair of interceptions - one in the end zone - that led to 10 points and a 20-17 Cincinnati lead early in the fourth quarter.
That's when the Broncos (5-3) have been at their best.
Manning threw a 1-yard touchdown to tight end Joel Dreessen that put Denver back ahead. After Andy Dalton underthrew a pass under pressure that was picked off by Champ Bailey, Manning put it away with a 4-yard pass to Eric Decker with 3:36 remaining.
(KUSA-TV © 2012 Multimedia Holdings Corporation)