The Bears (14-15, 4-12 Big 12) led 75-62 on a layup from Josh Lomers with just over seven minutes remaining.
But the Cowboys (20-10, 6-9) scored 10 straight, cutting the margin to 75-72 at the 4:09 mark.
Jerrells 3-pointer put Baylor ahead 80-72 with a little over two minutes left to play. But then JamesOn Curry, who led all scorers with 40 points, nailed three straight free throws to pull Oklahoma State to within three points at 80-77 with 1:17 to go.
The Bears responded with six consecutive free throws, four by Aaron Bruce and two by Jerrells, in the final 41 seconds to clinch the win.
The Bears, who led 41-32 at halftime, opened the second half with a 10-4 run, extending their margin to 51-36 with just over 17 minutes remaining.
Baylor led by as many as 18 points at 64-46 midway through the second half.
Mario Boggan, Oklahoma State's leading scorer, did not play against the Bears. Cowboy head coach Sean Sutton suspended Boggan following a video review of a head butting incident against Cartier Martin of Kansas State that occurred last Tuesday.