With 3:48 left to play, Penn State freshman Josh Reaves fouled Marc Loving as he was shooting behind the arc to send the Ohio State forward to the free throw line.
Loving made all three foul shots to give the Buckeyes a three-point lead.
The Buckeyes scored four more unanswered points on two layups from guard JaQuan Lyle.
Six free throws later, the Buckeyes (20-12) had enough of a cushion to hold off the Nittany Lions, 79-75.
The Buckeyes led 18-15 with 10:23 left in the first half before Lions guard Shep Garner drove to the hoop for a layup, sparking a 10-0 Lions run.