Oregon (12-1) jumped out to a 15-0 lead behind Thomas’ opening return and 23-yard touchdown catch in the first quarter.
Kansas State (11-2) tried to bull its way behind Heisman Trophy finalist Collin Klein, only to get overwhelmed by the speedy Ducks, who got some help with an obscure 1-point safety on a blocked extra-point kick.
Mariota added a 24-yard touchdown pass to Kenjon Barner in the second quarter and ran for a 2-yard score in the third to give Oregon its second consecutive BCS bowl win after beating Wisconsin in last year’s Rose Bowl.
Klein threw two interceptions and had 30 yards rushing on 13 carries.
Oregon was awarded a 1-point safety on an obscure rule midway through the third quarter. Mariota scored on a 2-yard run midway and the Ducks sent kicker Alejandro Maldonado out to kick the extra point.
Kansas State’s Javonta Boyd blocked the kick and the ball ended up in the hands of teammate Chris Harper, who was tackled in the end zone.
After a review of the play, the officials awarded the Ducks a 1-point safety that put them up 32-10. It was the first such 1-point safety in major college football since Texas got one against Texas A&M in 2004, STATS said.