"This is clearly the biggest win in the history of the school," Gundy said. "You're in a New Year's Day bowl. You're playing Notre Dame. Biggest comeback in the school history. ... The biggest win in the history of the school."
Oklahoma State rallied from a 28-7 deficit in the second quarter to score 30 straight points. The team's previous biggest comeback was 20 points down against Colorado in 1979.
The Cowboys won 12 games for the first time under Gundy, a former Oklahoma State quarterback in his 17th season as head coach.
Oklahoma State also won the Fiesta Bowl after the 2011 season to finish No. 3 nationally. This season, Oklahoma State ended a six-game losing streak to rival Oklahoma, and it made its first Big 12 championship game appearance but fell to Baylor as running Dezmon Jackson was stopped inches short of a potential winning touchdown.
"We feel like if we didn't win this game, this would be kind of a season of just forgotten greatness," defensive end Brock Martin said after the Fiesta Bowl. "We lost the Big 12 championship, and then you lose the Fiesta Bowl, all that greatness and the great things you did as a unit, the D-line and linebackers and DBs, we kind of felt like it would be forgotten over time."
Oklahoma State quarterback Spencer Sanders finished with 371 passing yards and four touchdowns to go with 125 rushing yards on 17 carries. He joined former Clemson quarterback Tajh Boyd as the only FBS players to record 350 pass yards, 100 rush yards and four touchdowns in a bowl game.
Gundy said the Cowboys' maturity and experience kept him optimistic when the team fell behind by three touchdowns.
"They're veterans," Gundy said of his players. "They've been in this program, most of them -- particularly on defense -- been in the program four, five, six years. For that reason, I didn't have any concerns. I was just hoping that we could hold up with the length they had on both sides of the ball up front."
Notre Dame's loss spoiled the head-coaching debut for Marcus Freeman, promoted Dec. 3 from his defensive coordinator spot to succeed Brian Kelly. The Irish fell to 0-8 in BCS or New Year's Six bowls, the most losses by any team without a win. Their most recent win in a bowl that is now part of the New Year's Six was the 1994 Cotton Bowl Classic.
"For me, as the leader of this program, it's a pit in your stomach ... that you want to bottle it up, and you want to remember how this feels," Freeman said. "The honeymoon stage is over, right? The whole new head coach, it's a great story. No, it's about having a great product, and it's about having a great team. So we have to make sure that it's about developing this team for next year. This year's over. So everything we do from now moving forward is going to be development and making sure we're prepared to have success."
Freeman added: "We're going to use this game as motivation. We're going to use this game to look back and say, 'Remember that first one? Look where we've come from there.'"
Quarterback Jack Coan, playing his final game for Notre Dame, passed for 509 yards, the second-highest single-game passing total in team history, and five touchdowns.
After Oklahoma State scored to cut its deficit to 28-14, Notre Dame took over at its own 25-yard line with 37 seconds left in the first half and all three timeouts. But the Irish elected to run out the clock, not wanting to risk a potential turnover, Freeman said.
"I wouldn't change that," he said. "We all can learn from it and look at every situation."