Originally a linebacker, Bell first attracted notice during his sophomore season at USC in 1974 as a great blocker and between-the-tackles runner, sharing the position of fullback with David Farmer for the national championship team that defeated third-ranked Ohio State 18–17 in the Rose Bowl on New Year's Day. In 1975, the Trojans won their first seven games. Without a passing game to balance the offense, they struggled to an 8–4 record, but was capped with a victory over Texas A&M in the Liberty Bowl. During this season, Bell led the nation in rushing, gaining 1,875 yards, as he finished third in the voting for the Heisman Trophy and was a consensus All-American. Then in his senior season of 1976, Bell led the Trojans team to an 11–1 record, crowned by a 14–6 victory over the Michigan Wolverines in the Rose Bowl. Despite suffering nagging injuries that limited his playing time, Bell set the USC single-game rushing record of 347 yards against Washington State at the new Kingdome, and he was the runner-up for the Heisman, behind Tony Dorsett of Pittsburgh, the national champions. Bell was voted the player of the year in the Pacific-8 Conference in 1976. He was also awarded the 1976 W.J. Voit Memorial Trophy as the outstanding football player on the Pacific Coast and was again a consensus All-American.
NFL career
Bell was the first overall draft choice in the 1977 NFL Draft, selected by the Tampa Bay Buccaneers, who were winless in their first season in 1976. Bell signed a five-year contract for a reported $1.2 million, by far the richest contract ever signed by an NFL rookie. This draft choice was somewhat controversial because Tony Dorsett was being projected as an arguably better back than Bell. Bell's selection was not a surprise, however, because Tampa Bay was coached by John McKay, Bell's former head coach at USC through 1975. After a couple mediocre seasons, in 1979, Bell enjoyed his finest season, rushing for 1,263 yards and leading the Buccaneers to the championship of the NFC Central Division. He led the Buccaneers to their first playoff win in franchise history that season by rushing for 142 yards on 38 carries scoring two touchdowns against the Philadelphia Eagles. The team fell one game short of a trip to Super Bowl XIV, ending their season by losing to the Los Angeles Rams for the NFC championship. In March 1982, McKay sent him to the San Diego Chargers, but suffering from weight loss, aching muscles, and severe skin problems, he retired before the 1983 season.