Mahomes threw a touchdown pass of 1 yard to rookie wide receiver Marcus Kemp. He also lost a big play when his 41-yard toss to wide receiver Demarcus Robinson was wiped out by a holding penalty on tackle Isaiah Battle. He took his first professional sack, as well.
Mahomes finished 7-of-9 for 49 yards.
Coach Andy Reid should be fairly happy with Mahomes' performance as the rookie showed off some versatility in the Chiefs' 27-17 loss to the 49ers. In Week 2 of the preseason, Mahomes should see more action when Kansas City plays at Cincinnati next Saturday (7 p.m. ET).
Here's how the rookie's debut played out Friday night:
Your first look at Patrick Mahomes II on the Arrowhead Stadium field. He's out warming up with some teammates in advance of tonight's preseason opener against the San Francisco 49ers.
Rookie QB Patrick Mahomes II warming up prior to the Chiefs' preseason opener against the 49ers at Arrowhead Stadium.
Pat Mahomes is in at QB for the Chiefs.
Mahomes lost a 40-yard pass to Demarcus Robinson on his first play. It was wiped out by a holding penalty on tackle Isaiah Battle.
Mahomes is then sacked for the first time by San Francisco's Aaron Lynch.
The Chiefs wound up punting on Pat Mahomes' first possession. He went 2-of-2 for 13 yards.
Patrick Mahomes picked up his initial first down on Kansas City's first possession of the second half on a screen pass to De'Anthony Thomas.
Marcus Kemp was the recipient on Patrick Mahomes II's first preseason TD pass. Mahomes rolled right and fired to Kemp in the end zone from a yard out. Mahomes missed a TD pass earlier when he threw high for tight end Gavin Escobar in the end zone.
The Chiefs' possession ended after a Kansas City holding penalty. Patrick Mahomes II is 7-of-9 for 49 yards.
Pat Mahomes looks like he's just getting comfortable after throwing his first TD pass. He threw for 16 yards to Gehrig Dieter to get the next drive started.
Patrick Mahomes II is finished for this game. Fourth-string QB Joel Stave will play early in the fourth quarter with the Chiefs and 49ers tied at 17.
Patrick Mahomes II liked the call sent in for his first play with the Chiefs, a deep pattern that went for 41 yards to Demarcus Robinson. The play was wiped out, though, by a Chiefs penalty.