Selmon joined brothers Lucious and Dewey Selmon on the University of Oklahoma defensive line in 1972. He blossomed into a star in 1974, anchoring one of the best defenses in Sooner history. The Sooners were NCAA Division I-A national football champions in 1974 and 1975. Selmon won the Lombardi Award and the Outland Trophy in 1975. OU Head Coach Barry Switzer called him the best player he ever coached, and College Football News placed him as the 39th best college player of all time. He was known as “The Gentle Giant.” In the fall of 1999, Selmon was named to the Sports Illustrated NCAA Football All-Century Team.
Selmon was named a consensus All-American in 1974 and 1975 by Newspaper Enterprise Association. His long list of achievements, in addition to the Vince Lombardi Award and the Outland Trophy, includes the National Football Foundation Scholar-Athlete, GTE/CoSIDA Academic All-American and Graduate Fellowship Winner National Football Foundation and Hall of Fame.
His brothers Lucious Selmon and Dewey also were All-American defensive linemen for Oklahoma, and played on the same defensive line together in 1973. The trio is still regarded as the most famous set of brothers in OU history.
The 1996 Walter Camp “Alumnus of the Year” was voted to the Oklahoma Sports Hall of Fame in 1992.
In 1976, Selmon was the first player picked in the NFL draft, the first-ever pick for the expansion Tampa Bay Buccaneers. He joined older brother, Dewey, who was a second round pick of the Bucs. In his first year Selmon won the team’s Rookie of the Year and MVP awards. Selmon went to six straight Pro Bowls and was named NFL Defensive Player of the Year in 1979. Buccaneer assistant Abe Gibron said, “Selmon has no peers” at defensive end, while former Detroit Lions coach Monte Clark compared him to “a grown man at work among a bunch of boys”. A back injury made the 1984 season his last, and the Bucs retired his number, 63, in 1986. He is a member of the Florida Sports Hall of Fame. In January 2008, Selmon was voted by a panel of former NFL players and coaches to Pro Football Weekly‘s All-Time 3-4 defensive team along with Harry Carson, Curley Culp, Randy Gradishar, Howie Long, Lawrence Taylor and Andre Tippett. He was the first player to be inducted into the Tampa Bay Buccaneers’ Ring of Honor on November 8, 2009.