The victory was the Cyclones' first road win since defeating Texas A&M 42-14 in 2005.
Alexander Robinson scored on a 15-yard run in the third quarter, and rushed for 143 yards on 23 carries for the fifth 100-yard rushing game of his career.
Arnaud, who threw four interceptions and was benched in last week's loss to Iowa, was 13-for-21 for 144 yards. He also ran for 42 yards on nine carries.
Trailing 7-3 in the first quarter, Iowa State (2-1) scored two touchdowns in a span of 2:02 to pull away from the Golden Flashes (1-2).
Kent State took its only lead when quarterback Spencer Keith, making his first collegiate start, hit running back Dri Archer down the left sideline for a 44-yard touchdown that put Kent State up 7-3 midway through the first quarter.
Iowa State took control of the game from there.
Arnaud threw a 22-yard scoring pass to Jake Williams at the 4:57 mark of the first quarter and then ran 9 yards for another score with 2:52 left. He scored on a 3-yard run early in the second quarter. Mahoney added a 37-yard field goal late in the quarter.
Iowa State scored on a nine-play, 81-yard drive on its first possession of the second half, capped by Robinson's run.
Kent State was playing without star running back Eugene Jarvis, who suffered a lacerated kidney last week against Boston College and will miss the rest of the season.
Keith, a freshman, started in place of Giorgio Morgan, who has a sprained left ankle.
Keith threw an 8-yard touchdown pass to Derek McBryde in the fourth quarter.