They followed it up with the kind of Alamo Bowl performance that should put the Cowboys among the favorites to win the Big 12 in 2017.
Rudolph passed for 314 yards and three touchdowns and Washington caught nine passes for 171 yards and a score as the No. 13 Cowboys routed No. 11 Colorado on Thursday night.
Defensively, Oklahoma State (10-3) smothered a Buffaloes team that had played for the Pac-12 championship, holding them to 318 total yards and shutting them out for three quarters.
Rudolph picked apart an experienced but injury-plagued Colorado secondary with precise throws into coverage, and Washington and other receivers made the big plays.
"We felt like their secondary really hadn't been challenged all year," Rudolph said.
Rudolph even set up Oklahoma State's first touchdown when he caught a throw-back pass for 24 yards. His 5-yard TD pass to Washington made it 17-0 in the second quarter, and Rudolph had scoring throws to Blake Jarwin and Jhajuan Seales in the third to make it 31-0.
Colorado's best season in more than a decade — dubbed "The Rise" — ended with a thud: consecutive losses in the Pac-12 title game and the program's first bowl appearance since 2007.
Senior quarterback Sefo Liufau passed for 195 yards and ran for a touchdown for the Buffaloes (10-4), but was sidelined for part of the second and third quarters after limping off following a sack.
"We did something special. We didn't finish with an exclamation point ... but I wouldn't trade this season for anything," Liufau said.
Colorado: Thrust into the defensive play-calling role for the bowl game, Colorado safeties coach Joe Tumpkin had a tall order in trying to keep up with Oklahoma State head coach and offensive guru Mike Gundy. The Buffaloes were solid in the first half but had no answer for Washington. The receiver easily beat all-Pac-12 cornerback Chidobe Awuzie, who was struggling with a turf toe injury, on several catches. The defense eventually gave out in the second as the Cowboys piled on the points.
Oklahoma State: The Cowboys delivered one of the best defensive performances from a Big 12 team all season. The Cowboys beat up the Buffaloes quarterbacks and gave up a few big plays but didn't break near the goal line.
"We played with a savage mentality. We didn't want to let any points on the board," Oklahoma State safety Jordan Sterns said.
Colorado's record-setting senior quarterback has been hampered by injuries during his career and couldn't make it to halftime of his last game unscathed.
He limped off the field after taking consecutive sacks in the second quarter that aggravated a high ankle sprain that knocked him out of several games this season. Colorado's only two regular-season losses came when he was out.
"I don't know how much the guy weighs but when he lands on it, it's not comfortable," Liufau said.
Steven Montez, who was 1-2 as a starter this season, replaced Liufau for several series but had his second throw intercepted near the Oklahoma State goal line when he badly underthrew a flea-flicker. By the time Liufau returned, Colorado was trailing 24-0.
Colorado: The Buffaloes won't finish where they'd hoped but will still likely finish in the Top 25 to cap their season-long turnaround. Even with two losses, they've built momentum for the future under coach Mike MacIntyre.
"(The seniors) truly rose this program from the ashes," MacIntyre said. "It was a burnt house when these seniors got here."
Oklahoma State: A dominant win behind their most dynamic players and an impressive defense could push the Cowboys into a Top 10 finish. And oh, what might have been if not for the botched officiating at the end of a loss to Central Michigan in the second game of the season.
Colorado: The Buffaloes won't be a surprise team in 2017 and will have to follow their big season without Liufau and eight senior starters on defense. Colorado opens 2017 against Colorado State in Denver on Sept. 2.
Oklahoma State: The Cowboys expect to be a big factor in the Big 12 in 2017 with Rudolph and Washington leading as many as 13 returning starters. Their season opener is Sept. 2 at home against Tulsa.