In his senior year (1969), the tackle spearheaded Penn State on defense with 89 tackles and was a unanimous All-America choice and All-East selection. He also finished fifth in the Heisman Trophy balloting.
Reid was the first-round selection (#7 pick overall) of the Cincinnati Bengals in the 1970 NFL Draft. In the team's third season, it won the AFC Central Division and made the playoffs. In 1971, Reid established himself as one of the NFL's best pass rushers by recording 12 sacks, a figure he repeated in 1972. In 1971 Reid was a consensus All-AFC selection and the following year he was consensus All-Pro as well as being voted consensus All-AFC again.
In 1974, due primarily to injuries, he recorded only seven sacks, bringing his career total to 49. In his final season Reid was again an All-AFC selection by Pro Football Weekly. Although sacks were an unofficial statistic, the Bengals kept track of them and Reid retired as the leading sacker in the team's short history.
He made two trips to the Pro Bowl (1972 and 1973) before his retirement following the 1974 season due to knee and hand injuries and his desire to focus on a music career. In 1996 he received the NFL Alumni Career Achievement Award for his success in his post-NFL career.
In 1990, Reid signed to Columbia Records as a recording artist. His debut album Turning for Home produced a Number One country hit in its lead-off single "Walk on Faith", although the album's other singles were not as successful. His second and final album, 1992's Twilight Town, produced two singles which both missed the Top 40, and he was dropped from Columbia soon afterward.
By 1991, Reid composed the music for the Civil War musical A House Divided. After that he wrote six more musicals/operas, including Quilts, Different Fields, Eye of the Blackbird, Tales of Appalachia, In This House, and The Ballad of Little Jo, a Richard Rodgers Awards for Musical Theater winner.