LaQuinton Ross came off the Ohio State (6-1) bench to rack up 16 points and nine rebounds in the Buckeyes' 36th consecutive non-conference win on their home court.
Lenzelle Smith scored 14 points and had nine rebounds.
Ohio State outrebounded the 49ers (3-6) 45-31.
Dan Jennings led Long Beach State with 16 points and James Ennis had a dozen. The loss extended the 49ers losing streak to three games.
Ohio State took a 39-25 lead into the second half and led by as many as 40 points down the stretch.