Mason-Griffin scored 38 points and Davis added 24 for the Sooners (12-8, 3-3 Big 12), who are 10-0 at home and 2-8 on the road.
Iowa State (12-8, 1-4) had six double-figure scorers, led by Diante Garrett's 17.
Craig Brackins, who had been averaging 16.0 points and 7.8 rebounds, was held to 13 points and six rebounds.
Oklahoma led by 18 points, but Iowa State cut the deficit to three points four times in the second half, the final time with 6 seconds left. The Sooners clinched it by making 7 of 8 free throws in the final two minutes.
After a season that saw his shooting numbers slip, should Nigel Hayes return for his senior year at Wisconsin or take the gamble to put him name in this year's NBA draft?
Isaiah Taylor talks about his decision to declare for the NBA draft and what he will miss most about Texas.
Chattanooga women's basketball coach Jim Foster has received a one-year contract extension, the same day the school gave the men's coach a two-year extension.