Pittman made all five of his field goals and scored nine points in a key run in the second half to push the Longhorns (22-6 8-5 Big 12) to just their fifth win in 11 games after a 17-0 start that saw them reach No. 1.
Damion James led Texas with 19 points. It was the first game for Texas since losing starting point guard Dogus Balbay for the season with a knee injury. Justin Mason played a key role in holding Big 12 scoring leader James Anderson to 14 points.
Obi Muonelo scored 14 points for Oklahoma State (19-8, 7-6).
The Longhorns have now consecutive games for the first time in more than a month, and this one guaranteed they will finish no worse than 8-8 in league play.
For Pittman, it was the first time in weeks he was able establish himself as a force in the post. His 16 points was the most for him since he had 21 in a win over Arkansas back on Jan. 5.
The Cowboys had little to stop him. On one early basket, an ill-timed defensive switch left 5-foot-9 Cowboys guard Keiton Page matched up against the 6-10, 290-pound Pittman under the basket. The big man easily won that battle.
Defensively, Mason and Avery Bradley applied the pressure on Anderson, who had scored at least 30 points five times this season but got little to fall when given little room to work against the Longhorns. Anderson shot 5 for 13.
Oklahoma State made eight 3-pointers after making 14 in a win over Baylor in the previous game, with just two after halftime.
James carried Texas early, scoring 15 points to lead the Longhorns to a 37-35 halftime lead. A 3-pointer by Muonelo had tied it before the Cowboys' Jarred Shaw fouled Pittman, then was whistled for a technical foul for jawing with him. Texas made two of the four free throws.
Pittman controlled the first 10 minutes of the second half, scoring nine of Texas' first 12 points and diverting shots on the other end.
After Oklahoma State had closed a six-point deficit to 44-42, Pittman thundered home his second dunk of the half and made a free throw for the three-point play.
When Texas lost Balbay for the season, they also figured to be losing their best perimeter defender. But Mason and Bradley were able to lock down on Anderson for long stretches, never letting him find his range or an open look at the basket
Bradley's 3-pointer from the left corner put Texas up 54-44 with 9:53 to play, the first double-digit lead of the game. After Pittman hit another tough basket in the lane, a steal by Bradley let to an easy layup that put the Longhorns up by 14.