The unbeaten Buckeyes came into the game having allowed 54.6 points per game, third best in the country, but the Blue Hens outshot Ohio State from the field 42 percent to 40.
The 64 points produced by Delaware were the second most surrendered by the Buckeyes this year.
Ohio State (11-0) outrebounded the Blue Hens 40-29. Aaron Craft contributed 14 points for the Buckeyes, who had an 11-point halftime lead, and Lenzelle Smith, Jr. had 12.
Devon Saddler scored 17 points for Delaware (5-6).