Bell's key basket gave him eight points for the game while Kevin Pangos netted 23 points on 7-of-12 shooting and distributed five assists for the Bulldogs (13-1).
Kelly Olynyk finished with 21 points and nine rebounds as Gonzaga notched its fourth straight win since a Dec. 8 loss to Illinois.
Oklahoma State (10-2) fell despite 23 points and six assists from freshman Marcus Smart.
Markel Brown (16 points) and Phil Forte (15) also turned in good performances in the Cowboys' loss, which broke a five-game winning streak.
2014: The Year in Music [PHOTOS]