UCLA (10-0) overcame a sluggish first half and dominated the boards on the way to its 10th straight win of the season.
Ohio State (9-2) began the game leading 7-0, forcing two turnovers.
But the Bruins battled back. The two teams were tied at 17-17 after a first quarter that saw the Buckeyes go cold late, shooting two for 11 to close the period.
UCLA shot a game-high 53.8% in the second quarter, and the Bruins had a 37-31 halftime lead.
Osborne went four of 12 in the second half and led UCLA with 14 points over the final two quarters.
The Bruins led by as many as 22 points in the fourth quarter.
Kiki Rice had 15 points and Gabriela Jaquez had 11 points for the Bruins.
Ohio State used a 12-3 run late to get to within four points with six seconds left, but Osbourne made two free throws to close it out for UCLA.
Jacy Sheldon scored a game-high 30 points and Taylor Thierry had 20 for the Buckeyes.
The Bruins’ 10th win in a row was also their second straight over a ranked opponent. They are 3-0 against ranked opponents this season with wins over Connecticut, Florida State and the Buckeyes.
Up next:
UCLA hosts Hawaii on Thursday at 1 p.m. at Pauley Pavilion.