Mathis was 7-of-14 passing for 145 yards, connecting for three touchdowns, and he also carried the ball nine times for 31 yards. Only one of Mathis' seven completions did not go for a touchdown or a first down.
The sophomore got the start after Jennings was hurt early in last week's game at Walton.
"I was really proud of Jordan Mathis (on Friday) stepping in there and playing for Anthony," Marietta coach Scott Burton said. "Jordan is a very intelligent, very athletic football player. We are certainly glad to have him."
Marietta (5-5, 5-1 Region 5AAAAA) held Cherokee (1-9, 0-6) to 74 total offensive yards in the first half and held the Warriors to 122 yards until a late, 80-yard touchdown drive in the fourth quarter.
"We wanted to make sure we gave our seniors the opportunity to go out on a winning note," Burton said. "They have meant a lot to this program. Those guys have really been the leaders of this team. Cherokee is physical, but our guys rose to the occasion."
Those seniors will get at least one more game under their belt, beginning next Friday when Marietta hosts Centennial, the No. 3 seed from Region 6AAAAA, in the opening round of the playoffs.
Cherokee took the ball first and ground out a 10-play drive, but the Marietta defense stopped the Warriors on fourth down. The Blue Devils went 75 yards on 16 plays, and running back Ro'Mello Porter scored the opening points of the game on a 4-yard touchdown run with 2:14 left in the first quarter.
Marietta scored the next 21 points and shut the Cherokee offense down.
"We wanted to start fast, and Cherokee took that away from us a little bit," Burton said. "It was a slow start, but it wasn't a bad start. We were able to pick up some momentum there as the first half unfolded."
Mathis connected with wide receiver Kenny Norwood for a 31-yard touchdown pass on the Blue Devils' first possession of the second quarter. Mathis found wide receiver Tyree Harris on a screen pass and Harris took it 44 yards for a touchdown in the second quarter.
Mathis later used play-action and found wide receiver Marcus Bennett wide open in the end zone for a 19-yard touchdown in the third quarter.
Burton said his message to his team before this week's game was simple with the playoffs beginning next week.
"The outcome of this game didn't matter, but it mattered so much," Burton said. "We didn't need to win the game to change our seeding, but we needed to win the game. That was the message all week long. Don't worry about what the people say about this being a meaningless game."
Cherokee quarterback Hunter Wingfield connected with split end Trey Butler for a 29-yard touchdown with the fourth quarter winding down.
Cherokee coach Brian Dameron was glad to see his team fighting until the end.
"We sure would have liked to have some more wins this season, but I want to thank those guys for continuing to fight and continuing to believe especially when it is hard to do that," Dameron said. "We have to continue to believe and execute. And when you are not winning a lot of football games, it is easy for guys to mail in their effort, and I don't think our guys did that."