Lambert connected from 27 and 34 yards late in the fourth quarter to produce his team's only second-half points, and nail down the win for the Mountaineers (3-2, 1-1 Big 12).
Clint Trickett, the third quarterback to start for West Virginia this season, was 34-of-50 passing for 309 yards and a touchdown. Charles Sims ran the ball 18 times for 60 yards and a touchdown.
J.W. Walsh was 20-for-47 for 322 yards and three touchdowns for Oklahoma State (3-1, 0-1). Walsh ran the ball 16 times for 52 yards.
West Virginia led 24-14 at halftime and limited Oklahoma State to a 30-yard touchdown reception by Jeremy Seaton in the third quarter. The Cowboys had won their first three games by an average of nearly 32 points.