Star senior guard Tayler Hill led all scorers with 23 points for the Buckeyes, who used a 12-2 run midway through the second half to break open a close game in front of 2,625 fans at Value City Arena.
There were three ties and a pair of lead changes in the first half as the visiting Red Flash (3-1) cut what had been a seven-point deficit to three points by the time intermission arrived.
The difference hovered between three and eight for the first seven minutes of the second half until seniors Hill and Amber Stokes got the Buckeye offense revved up with the help of freshman guard Ameryst Alston.
Stokes started the decisive run with a fastbreak layup she mostly created on her own with her speed, and Hill kept it going with a three-pointer that made it 52-44 with 12:04 to go.
Hill added three more on an old fashioned three-point play, then Stokes answered a Saint Francis basket with another layup to push the lead back to double digits at 57-46.
Alston then picked the pocket of Alexa Hayward and sped toward the OSU basket for a layup that prompted Saint Francis head coach Joe Haigh to call timeout with 9:04 remaining in the contest.
By then, it was too late. The 16th-ranked Buckeyes would go on to lead by as many as 18 before closing out the victory.
Hill scored her 23 points on 6 of 15 shooting. She hit a trio of triples and went 8 for 10 from the free throw line while grabbing five rebounds and snagging five steals. She also had five turnovers, four of which came during a somewhat inefficient first half.
The Buckeyes shot 52.2 percent (12 for 23) in the first half but committed 12 turnovers. They gave the ball away only seven times after the break and scored 38 points despite shooting a slightly lower percentage (48.0) from the field (12 for 25)
"We slowed down," Hill said. "I think that was the biggest difference. We were reversing the ball. We were just playing entirely too fast in the first half and that's on me being the point guard."
For the game, Stokes had 12 points while Alston contributed 10 off the bench. The reshuffled front line of Darryce Moore and Martina Ellerbe added another 10 points apiece to give Ohio State head coach Jim Foster a balanced scoring effort.
He had to move Moore to center to start the game with Ellerbe entering the lineup to replace regular starting center Ashley Adams, who aggravated a quad injury during practice Monday and is considered day to day.
Haigh said Adams' injury did not alter how the Red Flash chose to play defense, but the Buckeyes had to adjust without her. They kept their usual strategy of spreading the floor and looking for open shots, but that became harder to execute without Adams' natural ability to keep the ball moving and find open teammates.
Junior forward Alli Williams scored 16 points to lead the visitors, but she fouled out with 6:33 to go while trying to box out Ohio State's Amy Scullion.
Scullion played a career-high 15 minutes and grabbed four rebounds while filling the No. 4 spot for much of the second half. Foster inserted her into the lineup and moved Ellerbe to center to enhance the team's rebounding. Ellerbe was an efficient 4 for 4 from the field and grabbed five boards in her 33 minutes of action.
"We needed some rebounds and Martina and Amy were getting them," Foster said. "This team showed we have versatility. People picked up when Adams wasn't out there. It's nice to know we can have that kind of distribution on our stat sheet."
Also scoring in double figures for the Red Flash were guard Alexa Hayward (13 points) and forward Shené Fleming (11).
"I am proud of our effort and I am happy I can say that," Haigh said. "I was happy with the way we executed our defensive game plan for the most part. I'm not as happy with our offense, but we played really hard and we competed."