DENVER (AP) -- Patrick Mahomes II made both his first NFL start and his first NFL relief appearance a success Sunday, leading the Kansas City Chiefs past the Denver Broncos 27-24 on Harrison Butker's 30-yard field goal as time expired.
Starting in place of Alex Smith, Mahomes handed off a 24-10 lead to No. 3 QB Tyler Bray midway through the fourth quarter but came back with the score tied at 24 and less than three minutes left.
He drove the Chiefs 67 yards in 11 plays for the game-winning field goal that sent the Chiefs (10-6) to their fifth straight win over the Broncos (5-11).
Mahomes became the first quarterback drafted by the Chiefs to win a game for them since Todd Blackledge in 1987. He threw for 284 yards on 24-of-35 passing with no touchdowns and an interception.
Broncos QB Paxton Lynch was 21 of 31 for 254 yards with two TDs, two interceptions and was sacked five times.
Rookie Kareem Hunt scored on a 35-yard run on his only carry, securing the NFL rushing title over Todd Gurley II and Le'Veon Bell, both of whom were inactive Sunday. And C.J. Anderson gained 61 yards to top 1,000 for the first time in his five-year with the Broncos.
The Chiefs rested QB Smith and several other starters because they were locked into the No. 4 seed in the AFC playoffs, allowing coach Andy Reid and his staff to essentially use this regular season finale as their playoff bye.
Bray handed off late to fullback Anthony Sherman — who carried 14 times for 40 yards after coming into the game with six career carries in seven NFL seasons — and linebacker Zaire Anderson scooped up the loose ball and scored from 38 yards out.
Lynch added a 6-yard TD pass to Demaryius Thomas with 2:53 left, and Brandon McManus' extra point tied it at 24.
Mahomes returned to the game with 2:45 left and was promptly sacked by DeMarcus Walker but recovered nicely to drive K.C. to victory.
Lynch threw an interception late in the first half and was sacked three times in a five-snap span in the third quarter, losing the ball on one of them with linebacker Ramik Wilson scooping it up and scoring from 11 yards out.
Mahomes made a good first impression, connecting with tight end Demetrius Harris for 51 yards on third-and-10 from his own 14 on Kansas City's opening drive. Then, he handed off to Hunt, who dashed for a 35-yard touchdown less than a minute into the game.
Kansas City moved up 17 spots to take the Texas Tech standout quarterback last April, ending three decades of avoiding quarterbacks in the first round. He watched all year as Smith had the best season of his 13-year career, throwing for 4,042 yards to go with 26 touchdowns and just five interceptions.
Mahomes was intercepted by Darian Stewart on his second drive but engineered a 73-yard TD drive that Sherman capped with a 1-yard run to give Kansas City a 14-10 halftime lead.
It was 17 degrees at kickoff, the fifth-coldest home start in Broncos history and the coldest temperature for any of Lynch's starts, in the pros or at Memphis.
Just like he did at Oakland a month earlier, Lynch struggled after throwing an interception. But before that, he threw a screen pass that rookie running back De'Angelo Henderson turned into a 29-yard score .
CLADY HONOR: The Broncos honored retired tackle Ryan Clady during the game. The 12th overall selection out of Boise State in 2008, Clady was one of the best linemen in team history but he was often injured in his career, missing both of Denver's Super Bowl appearances during his playing career.
INJURIES: Chiefs backup punt returner De'Anthony Thomas was carted off after injuring his right leg on the final play of the first quarter. He was dragged down by Marcus Rios after backtracking to field Riley Dixon's punt at his 5. CB Phillip Gaines was knocked out with an elbow injury just before halftime.
Broncos S Will Parks went out in the fourth quarter with a neck injury.
UP NEXT: The Chiefs turn their attention to the wild-card round of the AFC playoffs, where the Chiefs are seeking their first playoff win at Arrowhead Stadium in their history. The Chiefs will host the Tennessee Titans on Jan. 6.
The Broncos head into another offseason where the only certainty is change.