Austin Seibert's second field goal of the day made it 41-17 Sooners with 2:14 to play in the penultimate quarter.
Oklahoma is once again up three scores after a 52-yard touchdown pass from Baker Mayfield to Marquise Brown.
TCU quarterback Kenny Hill was stopped just short of the first-down marker on a fourth-down run to give the ball over on downs at the OU 40.
After an anticlimactic opening drive of the second half for TCU, Oklahoma needed just one play to go 55 yards for a touchdown. TCU's defense had given up only three second-half points over the last six games.
TCU vs OU: Stats | Play-by-play | Game view
TCU settled for a short field goal with seven seconds left in the first half after a questionable play call that saw Kenny Hill keep the ball for a one-yard gain on first down.
Oklahoma's Mark Andrews, who looks like a giant among boys, grabbed his second touchdown of the game to put the Sooners up 24-14. Andrews has been targeted nine times in the game, catching six of them.
A ridiculous one-handed catch by John Diarse brought the Frogs within three with 7:44 to play in the first half. The ball appeared to come out at the very end of the circus grab and was ruled incomplete, but the call was reversed to a touchdown after review.December 2, 2017
TCU went 74 yards on nine plays for the score.
Baker Mayfield took a quarterback keeper 54 yards deep into TCU territory, but a missed field goal kept the score at 17-7.
Jalen Reagor, the Big 12's co-offensive freshman of the year, grabbed a 29-yard touchdown pass from Kenny Hill to give the Frogs life on the second play of the second quarter.
Oklahoma took a 17-0 lead on a Baker Mayfield playaction pass to Mark Andrews. The drive was spurred by a 29-yard catch-and-run by Marquise Brown on 3rd-and-12. It's the largest lead after one quarter in Big 12 Championship game history.
The Horned Frogs drove 29 yards on six plays before punting it away on their second possession.
On TCU's first play from scrimmage, running back Kyle Hicks fumbled and OU's Caleb Kelly took it 18 yards to the house.
Oklahoma converted on a 3rd-and-7 and 4th-and-2 to keep its opening drive alive before settling for a 41-yard field goal to go up 3-0 with 10:30 left in the first quarter.