It did not come easy for the Buckeyes (17-8, 8-4 Big Ten), however. A Butler turnover led to a basket by Jeremy Nash that pulled the Wildcats within a point, 35-34, at the 13:56 mark of the second half.
But OSU used both its size inside and its accuracy outside to put together a 19-4 run, capped by a three pointer by freshman guard Jon Diebler, seizing control at 54-38.
From there, head coach Thad Matta's 200th career victory was just an inevitability.
"It's funny: you do this long enough you're probably going to get there," Matta told the Ohio State Basketball Radio Network of his milestone victory. "All it means is I'm getting older and older. The hard part is I can name every single loss but I can't name every win."
Of his 200 wins, 98 have come as the head man for the Buckeyes.
The game was marred by sloppy play on both sides. OSU committed 18 turnovers, and the Wildcats converted those miscues into 20 points. For its part, Northwestern (7-15, 0-11) committed 17 turnovers that OSU turned into 16 points.
The Wildcats' undoing proved to be its inability to shoot during the second half. After going 4 of 8 from beyond the three-point arc in the first half, Northwestern was just 9 for 28 overall (32.1 percent) from the field in the second half.
The Buckeyes, led by Diebler, went 5 for 11 from deep in the final 20 minutes, helping pull away.
However, they were aided just as much by their play in the paint. OSU had 30 points near the basket, led by Koufos' 16 points on 7 of 10 shooting. Senior forward Othello had the other 14 while also contributing five rebounds.
"It's what we wanted to do," Matta said of establishing a presence in the paint. "With the defense that they play there's going to be a little guy down there momentarily. I thought we did a good job of finding them down there."
In all, four Buckeyes scored in double digits. Butler had 12 points to go along with his six assists while freshman guard Evan Turner had 10 points thanks to a 2-for-2 performance from beyond the arc.
"I think that's the big thing that I said before the game: we get two guys playing and then next game it's two different guys," Matta said. "Hopefully we can build us some momentum off of that."
OSU's lone starter to not score in double digits was sophomore swingman David Lighty, who continued to struggle on the offensive end. The Cleveland native was just 1 of 4 from the field for two points and committed four turnovers.
A modest 5-0 run near the midway point of the first half gave the Wildcats a 19-18 lead, but the Buckeyes used two freshman to reclaim the upper hand. One possession after guard Craig Moore connected on a jumper to put Northwestern up one point, OSU countered with a three pointer by guard Evan Turner that rolled around before falling, putting the Buckeyes ahead by two. Following turnovers on the ensuing three possessions, center Kosta Koufos converted a reverse layup to push the lead to four points.
The first half was fraught with turnovers. Northwestern did the Buckeyes one better, though, committing 11 to OSU's 10 in the first 20 minutes.
The Buckeyes pushed their lead to its highest point total of the half – seven points – on a tip-in by Koufos to make it 29-22 in the final minute of the half. However, Northwestern's Moore connected on a trey with around five seconds remaining to set the halftime score at 29-25.
It was the only basket in the final six minutes for the Wildcats.
After discussing his desire to expand the team's rotation during the past week, Matta managed to get freshman forward Dallas Lauderdale into the game in the first half. He was part of an OSU frontcourt that helped the Buckeyes outscore the Wildcats in the paint by a 14-4 margin for the first 20 minutes. In addition, OSU held a 15-12 edge on the glass.
OSU has now defeated the Wildcats 17 consecutive times.