The win put the Nittany Lions (9-0, 5-0) in command in the Big Ten and severely crimped the chances of the Buckeyes (7-2, 4-1) grabbing an unprecedented third consecutive outright league title and a piece of their fourth conference championship in a row.
Penn State, with coach Joe Paterno coaching from the press box for the fourth game in a row, solidified its position as a national championship contender and also erased the ugly memories of an 0-7 mark in Columbus since joining the Big Ten in 1993.
Defenses controlled most of the game before an Ohio Stadium-record crowd of 105,711.
Ohio State had the ball and a three-point lead when freshman quarterback Terrelle Pryor fumbled on third-and-1 early in the fourth quarter. Penn State linebacker Navorro Bowman fell on the loose ball at the Buckeyes' 38.
Clark was meeting with team doctors, so in stepped Devlin, who had seen action in seven games, but had only been on the field for 45 plays.
He promptly led the way on a seven-play, 38-yard drive that took 4:13 and ended with his touchdown giving Penn State a 10-6 lead.
The big play in the march came on third-and-2 at the Ohio State 6, when Royster skirted right end, tiptoeing along the sideline for a 4-yard gain and the first down.
Three plays later, Devlin scored on his second consecutive keeper, and Kevin Kelly converted the extra point for a 10-6 lead with 6:25 left.
Penn State's defense then forced an Ohio State punt, and with Royster carrying most of the load, the Nittany Lions almost ran out the clock. Royster went for 3, 10 and 9 yards on his first three carries before Devlin sneaked for a first down at the Ohio State 24.
While the Buckeyes were using all of their timeouts, the Nittany Lions kept it on the ground. They let the clock run down until Kelly converted a 35-yard field goal with 1:07 left to push the lead to 13-6.
Ohio State had one last chance to tie it, but Pryor's long pass to the goal line was intercepted by cornerback Lydell Sargeant with 27 seconds left.