With a playoff spot already secured, Smith was given a rest in Week 17, and Chiefs' 2017 first round pick Patrick Mahomes made his NFL debut against the Denver Broncos. Smith finished the 2017 regular season with 4,042 passing yards and 26 touchdowns, both career highs. He was named an alternate for the Pro Bowl, eventually replacing the injured Philip Rivers. Overall, in the 2017 season, Smith finished with 4,042 passing yards (8th in the NFL), 26 touchdowns, five interceptions, and a league-leading 104.7 passer rating. In the Wild Card Round against the Tennessee Titans, Smith had 264 passing yards and two touchdowns in the 22–21 defeat. He was also credited as being instrumental in the development of Mahomes.