Craft picked up two early fouls and spent two long stretches on the bench. But he was still the Buckeyes' best option on a tough offensive night for each team.
LaQuinton Ross added nine points for Ohio State (20-6, 7-6 Big Ten), which trailed 23-20 at halftime. The Buckeyes made 38 percent of their shots.
Illinois (14-12, 3-10) scored just nine points over the first 15:35 minutes of the second half.
While each team struggled with its shooting, defense also played a key role.
The Illini paid close attention to Ross, who was averaging a team-high 14.6 points. He had just one field goal in the second half and was 3 for 8 from the field for the game.
Rayvonte Rice, Illinois' leading scorer, had trouble getting open for much of the game. He had seven late points to finish with 11.
Illinois' shooting percentage was a sickly 29 percent in the first half. But the Illini still had the lead at the break, using their defense and a flurry of early 3-pointers to grab the advantage.
But that poor shooting percentage kept getting lower as the game went along.
The Illini hit just one of their first nine shots in the second half, a seven-minute stretch during which the Buckeyes put together a 10-2 run to take a 30-25 lead.
Egwu's jumper with 12:55 to play temporarily ended Illinois' scoring drought.
But the Buckeyes eventually pulled away. Amedeo Della Valle had a layup and Marc Loving made consecutive jump shots to put the Buckeyes up 38-29.
While the Buckeyes managed to find a little offense, Illinois was missing -- jumpers and finger rolls and even a dunk attempt by Jon Ekey that skidded harmlessly across the top of the rim.
Illinois went 8:14 without a field goal before Abrams tossed in a 3-pointer with 4:25 to play, making it 42-32.
The Illini have lost 10 of 11.