He recorded 28 sacks and 267 total tackles in those two seasons en route to winning the Lombardi Award and Outland Trophy in '75.
He then was selected first overall in the 1976 NFL Draft by the Tampa Bay Buccaneers, where he became a six-time Pro Bowl selection in consecutive years between 1979 and 1984, including NFL Defensive Player of the Year in 1979.
And he had an outstanding nine-year career before a back injury forced him to hang it up after the '84 season.
Two years later, the Bucs retired his No. 63 jersey and he eventually became athletic director at the University of South Florida.
In 2009, he was the first ever player to be inducted into the Bucs' Ring of Honor.
Friday, he suffered a serious stroke and Sunday he tragically passed away in Tampa, Fla., at the age of 56.
"The Sooner family is saddened by the loss of one of its greatest champions both on and off the field, Lee Roy Selmon," said former head coach Barry Switzer. "He was the winner of both the Outland and Lombardi Award, a two-time consensus 1st Team All-American with a record of 43-2-1, two consecutive national championships, and the No. 1 draft pick in 1976.
"In addition to his accomplishments in football, Lee Roy was an honor student and is in the NCAA Academic Hall of Fame exemplifying what every student athlete should aspire to be."
So, he had a lasting impact on OU and Tampa Bay with his production on the field, but what many remember him most for is his character.
"Lee Roy Selmon has always represented the true spirit of what it means to be a Sooner," said OU President David L. Boren. "He will always be remembered for his great talent, personal integrity and sincere concern for others. His example will continue to teach generations of student-athletes the true meaning of team work."
OU athletic director Joe Castiglione added onto that.
"To know Lee Roy Selmon was to count him among your most cherished friends," Castiglione said. "He exuded class and dignity. He was a great and decorated champion at Oklahoma, but far more than that, he lived life like a champion.
"Lee Roy was an example of what we hope all our student-athletes will become. Lee Roy, like everyone in his family, epitomized greatness, yet remained focused on the welfare of others."
Such a greatness, current head coach Bob Stoops said it was impossible not to feel the impact when around him.
"There was a sense of awe every time you were in Lee Roy's presence, and yet that was the last thing he would have wanted," Stoops said. "He accomplished so many things in life, but remained a humble, unassuming champion. I hold up many of our previous greats as examples for our current players and Lee Roy is among the very best. All of our players would do well to follow in Lee Roy's footsteps."
Indeed, they would from such a special person with such a legacy at OU.
"Beyond his many and great accomplishments, I believe the true legacy of Lee Roy Selmon lies within the kind of man he was," Switzer said. "Lee Roy possessed a combination of grace, humility and dignity that is rare. His engaging smile and gentleness left you feeling blessed to be in his presence. Best of all, he was all genuine. One would be blessed to have a father, son, uncle, brother or friend like Lee Roy Selmon."
And so is Sooner Nation for having the honor to call him one of its own.