During his time at North Carolina A&T University, Bethea was a three time Pittsburgh Courier Black College Football All-American. In college, he played offensive guard and tackle, as well as defensive end and linebacker. He was selected in the third round as an offensive lineman in the 1968 AFL/NFL draft by the Houston Oilers. He spent all 16 years of his NFL career with the Houston Oilers and played in 210 games, including a stretch of 135 consecutive. He was an eight-time Pro Bowl selection. He led the team in sacks six times, finishing his career with 105 unofficial sacks. In 1973, he recorded 16 sacks, which still ranks as the best in Oilers/Tennessee Titans history. When he retired, he held three team records relating to career service: most seasons (16), most career regular season games played (210) and most consecutive regular season games played (135). Bethea was elected to the Pro Football Hall of Fame in 2003.