Oklahoma State held the Bulls without a point for a 5-minute stretch early in the second half while building a 12-point lead.
The Cowboys (6-1) rebounded from their first loss of the season, a 10-point setback against Virginia Tech on Saturday. Markel Brown added 13 points for the Cowboys while Philip Jurick claimed 15 rebounds.
South Florida (5-3) had won its previous three games. Victor Rudd had 14 points for the Bulls while Anthony Collins scored 12.