Withey finished with four blocks to go with 13 points, nine rebounds and three steals for the Jayhawks (18-1, 6-0 Big 12).
“He's definitely a good shot blocker but (my play) is on my part,” M'Baye said. “I think I could have done a better job on shooting. It's the first time I've played against a 7-footer.”
Withey clearly affected the Sooners. They ended the night going 21-of-59 from the floor.
Oklahoma never cut the deficit to fewer than eight points in the second half, with Kansas leading by as many as 15.
Ben McLemore led Kansas with 18 points.
Osby and M'Baye had 12 points apiece to lead Oklahoma.
Osby did give Withey one piece of payback for dominating the Sooners, blocking a dunk attempt by Withey in the second half.
“He's a unique player not only in our league but in college basketball in terms of you don't play against those players very often,” Oklahoma coach Lon Kruger said of Withey. “You learn from the mistakes. He erases the mistakes on the perimeter plus he guards his own guy inside. ... It's that little difference that Withey provides that makes a difference in shooting.”