Hyde, who was suspended for the first three games after an alleged conflict with a female in a bar this summer, prevented that. He scored on a 4-yard run late in the third and added two more touchdowns in the final quarter to lift the Buckeyes.
He was credited with a 2-yard touchdown after a replay review early in the fourth to put Ohio State ahead 26-23.
Then, after Northwestern's Trevor Siemian connected with Cameron Dickerson on a 12-yard score, Hyde ran it in from the 7 with 5:22 left in the game. That made it 34-30.
The Wildcats' Kain Colter then got stopped on fourth-and-1 at the Ohio State 34 with 2:43 left after he picked up his own fumble, wiping out a late threat. The game ended with Northwestern (4-1, 0-1) lateralling and the Buckeyes recovering the loose ball in the end zone.
Ohio State pulled this one out even though Braxton Miller had a rough night. He threw for 203 yards but had an interception and fumbled twice after matching a career-high with four touchdown passes against Wisconsin last week. He also ran for 68 yards.
Corey Brown added 127 yards receiving, and the Buckeyes beat the Wildcats for the 29th time in 30 games.
Northwestern hasn't beaten a Top-five team since it opened the 1959 season with wins over No. 2 Oklahoma and No. 5 Iowa.
Siemian threw 245 yards and two touchdowns against a defense missing one of its leaders in safety Christian Bryant. He broke his left ankle late in last week's game and is expected to miss the rest of the regular season.
Kain Colter completed all 12 passes for 98 yards and had a touchdown catch early in the game.
Venric Mark added 60 yards rushing after missing three games with a lower body injury, but instead of a signature victory, Northwestern came away with a tight loss.
Northwestern was leading 23-20 early in the fourth when Doran Grant stepped in front of Rashad Lawrence to pick off a pass by Siemian at the 23. He returned it 7 yards to the Northwestern 16, and on third-and-goal at the 2, Hyde reached across the goal line and was credited with the touchdown after a replay review.
That delighted the Buckeyes fans, but the Northwestern crowd had plenty to cheer moments later.
Siemian connected with Lawrence on a 67-yard slant to the 7. Then, with the ball at the 12, a scrambling Siemian found Cameron Dickerson in the end zone on third down. Just like that, the Wildcats were back on top, 30-27, but in the end, it was Ohio State's night.