The Wildcats won their seventh in a row, having lost this season only to nationally-ranked Michigan and Gonzaga.
Kansas State outshot TCU from the field 48 percent to 37 and turned the ball over only six times. The Wildcats are 14-2 for the season and are unbeaten in three Big 12 Conference games.
Jordan Henriquez added eight points and 10 rebounds for Kansas State.
TCU (9-8, 0-4) was led by Adrick McKinney with 18 points. It was the Horned Frogs' fourth straight loss.