He entered the game with negative-4 yards rushing on 19 attempts, but that includes 36 yards lost on seven sacks.
On Saturday, the Wildcats (1-8) struck first with a nine-play, 80-yard drive that featured 61 yards on the ground.
The last 16 came from Evan Hull, who took a direct snap and juked cornerback JK Johnson at the line of scrimmage before going into the end zone untouched.
After spinning its wheels most of the first half, second-ranked Ohio State (9-0) finally got something going on its seventh possession of the day.
The Buckeyes took over at the Northwestern 46 after a short punt into the wind and needed six plays to find the end zone on a 15-yard end-around by Emeka Egbuka, who tight-roped the sideline inside the 5 and spun into the end zone at the goal line. Stroud kept the drive going two plays earlier when he kept the ball on a zone-read and picked up 16 yards on fourth-and-1.
Ohio State turned Northwestern over on downs to start the third quarter then turned around and took the lead on a 27-yard touchdown run by Miyan Williams.
He took a handoff up the middle, cut outside and outraced the pursuit to the end zone to put Ohio State on top 14-7 with 8:44 left in the third quarter.
Prior to that, he had carried 13 times for 28 yards.
After two more empty possessions by each team, Williams scored again to give Ohio State some breathing room with 4:21 left in the game.
His 2-yard isolation run was set up by Stroud’s surprise 44-yard run that caught the Wildcats off guard and was Ohio State’s longest play of the day by far.
“It just felt great to put some points on the board,” Williams said. “We expected to put way more points on the board. It’s a tough game, but I’m just glad we cam away with the win.”
Williams, who went the whole way at running back as TreVeyon Henderson missed the game with an injury, finished with 111 yards on 26 carries.
Stroud ran for 79 yards on six carries but completed only 10 of 26 passes, and his 76 yards represent Ohio State’s fewest passing yards in a game since the Buckeyes had 46 against Michigan State in 2015.
Hull finished with 122 yards on 30 carries for Northwestern, which ran for an Ohio State-opponent-season-high 206 yards.
Ohio State finished with 207 yards on the ground and avoided being outrushed in three straight games for the first time since the first half of the 2004 season.
The Buckeyes return home next week to face Indiana.
Indiana at Ohio State, TBD, 1410