The first 32 minutes were closely contested, but after Ohio State's Jantel Lavender tied the game at 63 with a layup assisted by Samantha Prahalis at the 7:44 mark, the Lady Rebels (6-3) went on a 14-4 run to open up a 10-point advantage.
The hosts' 77-67 lead with 2:58 remaining represented the largest lead of the game for either team and the best of times for the hosts, who did not score again.
Ohio State's Andrea Walker started the road back for the Buckeyes (10-1) by making a jumper in the lane on another assist from Prahalis, who stole the ball from Ole Miss leading scorer Bianca Thomas on the ensuing defensive possession to start a sequence that ended soon after with an Ohio State three-pointer by Sarah Schulze.
Buckeye Tayler Hill split a pair of free throws, then Schulze made another trey with 1:01 on the clock to cut the deficit to one.
After a turnover by Thomas, Hill tried to give the Buckeyes the lead with a three-pointer with 21 seconds left, but Walker grabbed the carom and was fouled to earn a pair of free throws.
The senior reserve center hit both freebies to put her team ahead 78-77 with 16 seconds left.
Kayla Melson missed a layup at the other end that could have put Mississippi ahead, and after Prahalis made 1 of 2 free throws, Rebel Elizabeth Robertson missed a potential game-winner as time expired.
Thomas, a senior guard, led all scorers with 25 points, including 18 in the first half. Melson and Shantell Black had 16 points apiece for the hosts.
Sophomore point guard Prahalis led Ohio State with 17 points, six assists and two steals while playing all 40 minutes. She also grabbed six boards but struggled from the field, making just 6 of 17 shots and none of her 6 from beyond the three-point line.
Schulze was the team's top deep threat, as usual. She made 3 of 5 from three-point range and finished with 14 points while Moeller and Brittany Johnson had 10 points apiece.
Lavender notched 15 points, 10 rebounds and three blocks.
Walker had six points and seven rebounds. She made game-winning free throws in the waning seconds for the second time in her career, matching a feat she first performed at Penn State as a freshman.