Smart won two high school state championships in the University of Texas' Frank Erwin Center. He returned for the first time Saturday to score 23 points, powering the 22nd-ranked Cowboys to their fifth straight win, 72-59 over the Longhorns.
"I have a great feeling for this gym," Smart said. "If felt great coming back."
Markel Brown added 17 points and Le'Bryan Nash had 14 points and nine rebounds for the Cowboys (17-5, 7-3 Big 12), who sputtered offensively for long stretches but were still able to shrug off a Texas team mired it its worst season in 15 years under coach Rick Barnes.
Cowboys coach Travis Ford had worried his team might be tired after emotional wins over Kansas and Baylor and sought to relieve the pressure by having his team play a game of whiffle ball on Thursday.
The result was a relaxed team, maybe a little too relaxed at times, that could overcome its own miscues to win.
"It wasn't pretty," Ford said. "We turned the ball over a lot but it's not something I'm really concerned with."
Ioannis Papapetrou scored 15 points to lead Texas (10-13, 2-8). The Longhorns shot 1 of 18 from 3-point range and were just 12 of 21 from the free throw line.
Texas' leading scorer this season, Sheldon McClellan, didn't score in the first half and finished with four points.
"They came in here fearless and really took it from us," Papapetrou said. "We didn't show up. We're embarrassed. More than frustrated, we're embarrassed."
Saturday marked the end of the 23-game NCAA suspension for Texas guard Myck Kabongo, who is expected to play the rest of the season.
Texas has clearly been hampered by his absence, which has forced the point guard duties to freshman Javan Felix, who had eight turnovers and one assist against the Cowboys.
Barnes called it Felix's "worst game" of the season and said Kabongo will start Wednesday night against Iowa State.
"There will be a different team on the court," Barnes said. "No doubt he has to start."
Despite its stumbles, Texas has still been able to use tough defense to force teams to grind out possessions looking for good shots. The Longhorns held Oklahoma State to 32 percent shooting in the first half.
Smart muscled his way to 11 points in the first half then dismantled Texas in the opening minutes of the second as the Cowboys asserted control.
A steal led to a fast break dunk before two free throws and a 3-pointer helped put the Cowboys ahead 42-30. Even when Texas could get physical with the Cowboys, Smart used his muscular frame to force his way past defenders for an easy floater in the lane, or step out for one of his three 3-pointers.
Brown scored six straight points in a 60-second burst that all but settled the game for the Cowboys. A dunk off a miss and a layup off a nifty pass under the basket from Smart put the Cowboys up by 14 points with about 8 minutes to play.
"It was a good win on the road. We respect Texas so much," Nash said. "We just keep trying to climb that ladder. We have great team chemistry."
Guard Naz Mitrou-Long, whose 2015-16 season ended in December due to hip problems, has been granted a hardship waiver for the coming season, Iowa State said.
As the Sooners look to life without superstar Buddy Hield and his sidekicks, it's clear their unseasoned players will need to grow up fast.
The Central Intercollegiate Athletic Association says it won't move its headquarters, its basketball tournament or other conference championships from North Carolina, despite