It wasn't a perfect performance for Marietta (6-5), which committed 11 penalties, but the Blue Devils were able to amass 448 yards of total offense to take the win and advance to a second-round showdown in south Georgia against top-ranked powerhouse Camden County.
"We were very sloppy," Marietta coach Scott Burton said. "The penalties and mistakes and things like that, I guess you can attribute that to a young team - obviously, nervousness in the first playoff game. But, I was proud of the way we executed. Centennial continued to fight throughout the game, but we continued to make plays as well, so it was a good overall win for us."
Quarterback Anthony Jennings contributed to six of Marietta's seven touchdowns, completing 13 of 22 passes for 241 yards and four touchdowns and rushing for 81 yards on 11 carries and two scores.
Running back Ro'Mello Porter rushed for 109 yards on 15 carries and a touchdown, while wide receiver Chavez Hemphill caught two passes - both of them for touchdowns - for 103 yards for the Blue Devils.
Centennial (5-6) got on the scoreboard first when Jimmy Meyer scored on a 1-yard quarterback keeper with 4:46 remaining in the first quarter, with the extra-point kick being blocked, to put the Knights ahead 6-0.
Marietta struck right back on the next offensive series when Jennings ran 37 yards for a touchdown and Jordan Mathis rumbled into the end zone for a 2-point conversion to give the Blue Devils an 8-6 lead with 4:01 left.
The Blue Devils increased their lead to 15-6 when Porter scored on an 8-yard run and Lawton Ward made the extra-point kick with 11:53 remaining in the first half.
Centennial closed the gap on the next series when Meyer threw a 40-yard touchdown pass to Christian Robinson and Conner Davis kicked the extra point to narrow Marietta's lead to 15-13 with 9:43 left in the first half.
It didn't take long for Marietta to respond as Jennings hit Hemphill for a 62-yard touchdown pass on the first play of the series and Ward made the extra-point kick with 9:23 left to push the Blue Devils' advantage back up to 22-13.
Jennings and Hemphill connected for another score later in the second quarter, this one for 41 yards with 2:12 left, and Ward kicked the extra point to give Marietta a 28-13 lead.
Centennial would get closer towards the end of the first time as Meyer scored on a 1-yard run with seven seconds left, with the extra-point kick falling short, to narrow the Blue Devil lead to 28-19 at halftime.
Jennings would provide Marietta with its final three scores in the second half, scoring on a 1-yard run, throwing an 18-yard touchdown pass to Tyree Harris and connecting with Marcus Bennett for a 30-yard scoring strike.