Andrew Fitzgerald scored 21 points to lead 73 victory against No. 18 Kansas State.
The Wildcats were coming off Tuesday's two-point loss to fourth-ranked Baylor, and ran into a Sooners team that shot 56 percent from the field.
Romero Osby and Steven Pledger both scored 18 points for Oklahoma (11-5, 1-3 Big 12), which hadn't won since beating Northwestern State on December 31.
Rodney McGruder had 19 points and 10 rebounds to lead Kansas State (12-4, 1-3), which made 10 three-pointers but shot 38.5 percent overall.