Oklahoma State chipped away at a 7-1 deficit to tie the game in the bottom of the ninth, but TCU got a 10th-inning home run from Zac Jordan for an 8-7 victory.
In the ninth inning Sunday, the Cowboys tied the game on a sacrifice fly by Zach Johnson that brought a runner home from third.
But Jordan answered in the top of the 10th with his home run, and Stefan Crichton (4-2) pitched out of trouble with two out and two on in the bottom of the inning for the victory.
The Horned Frogs improve to 33-14, having taken the series from the Cowboys. Oklahoma State fell to 31-15.