Tavarius Shine's jumper with 3:12 to play capped a 13-0 run for the Cowboys and pushed Oklahoma State to a 63-62 lead.
Dylan Osetkowski answered for the Longhorns with a runner with 1:50 left to allow Texas to leapfrog back in front at 64-63 and Mohamed Bamba's block of a layup by Sima with 48 seconds left allowed Texas to stay in the lead.
The Longhorns' Matt Coleman was then whistled for a charge with 23 seconds remaining, giving the Cowboys a chance to shoot for the win.
Shine drove into the lane from the left baseline after Bamba tripped in the paint, but was too strong on his jumper. The rebound was corralled by Sima, who tipped in the winning basket.
Jeffrey Carroll scored 17 points to lead the Cowboys (12-5, 2-3 Big 12). Brandon Averette added 11 points and Lindy Waters II scored 10 for Oklahoma State.
Eric Davis Jr. led the Longhorns with 18 points, while Osetkowski added 12 points and Bamba added 11 points (all in the second half) and grabbed 10 rebounds for Texas (11-6, 2-3).
Both teams slogged through a defensive first half with the Longhorns owning a 32-25 lead at intermission.
Texas outshot the Cowboys 41.4 percent to 35.7 in the first half and made five of its 11 3-pointers while Oklahoma State hit just 2 of 8 from beyond the arc. Davis Jr. led all scorers with 15 points in the first half while Waters III paced Oklahoma State with six points.
Davis didn't score in the second half until the 6:34 mark, but that basket helped the Longhorns quell an Oklahoma State mini-rally that had pulled the Cowboys to within 58-50.
--Field Level Media
Texas | Oklahoma State | |
Eric Davis Jr. 18 | Scoring | Jeffrey Carroll 17 |
Matt Coleman 5 | Assists | Lindy Waters III 3 |
Mohamed Bamba 10 | Rebounds | Yankuba Sima 7 |
Dylan Osetkowski 4 | Free Throws Made | Brandon Averette 5 |
Mohamed Bamba 1 | Steals | Thomas Dziagwa 2 |
Mohamed Bamba 2 | Blocks | Tavarius Shine 1 |
Team | Points | FG% | 3PM-3PA | FTM-FTA | Assists | Rebounds | Blocks | Steals | Turnovers |
Texas | 64 | 43.4 | 8-21 | 10-17 | 9 | 36 | 2 | 5 | 15 |
Oklahoma State | 65 | 44.8 | 3-10 | 10-13 | 11 | 26 | 1 | 8 | 7 |