Williams finished with 58 rushing yards on 16 carries and added 62 receiving yards on five catches as the Red Raiders (7-0, 4-0 Big 12) improved to 7-0 for the first time since 2008.
Davis Webb racked up 462 passing yards on 36-of-50 efficiency with two touchdowns -- both to Jace Amaro, who hauled down nine passes for 136 yards overall.
Bradley Marquez made eight grabs for 112 yards in the win.
The Mountaineers (3-4, 1-3) dropped a second straight as Clint Trickett was held to 27-of-43 through the air for 254 yards and one touchdown.
Dreamius Smith provided two scoring runs for West Virginia.