Kelsey Mitchell led the way with 29 points for the third-seeded Buckeyes, who avenged a 76-72 loss from the regular season and advanced to a Saturday semifinal showdown with No. 2 seed Iowa.
Ohio State took the lead for good on a layup by Alexa Hart that broke an 18-all tie with nine minutes left in the first half. That kicked off a 10-0 run that included two more baskets by Hart and one apiece from Mitchell and reserve forward Shayla Cooper.
The Buckeyes' lead reached as high as 15 points in the first half, and it did not slip into single digits until a layup by Minnesota's Carlie Wagner pulled the Golden Gophers to within 74-66 with 54 seconds left. Ohio State went 9 for 12 from the free-throw line after that to wrap up the win.
Mitchell, the Buckeyes' star freshman point guard, made 10 for 21 shots from the field and had four rebounds and four assists. She outscored fellow Big Ten Player of the Year Amanda Zahui B., but the Minnesota center logged a triple double with 25 points, 11 rebounds and 11 blocked shots.
Hart scored 17 points and had 11 rebounds, numbers matched by Cooper. The Buckeye duo also took turns making Zahui B. work hard for touches in the post, where she also had a hard time finishing.
Senior forward Shae Kelley also had a double-double for Minnesota, but the Buckeyes won the battle of the boards 48-47 after losing it 60-40 in the first meeting.
Ohio State turned 22 turnovers into 21 points and outscored the Gophers 10-2 in transition in front of 4,781 fans at the Sears Centre Arena in Hoffman Estates, Ill.
The Terrapins and Wildcats are set to play the first semifinal Saturday night at 7 with Ohio State (22-9, 13-5) taking on Iowa in the nightcap.
The Buckeyes and Hawkeyes split the season series with both teams winning on their home floor.