Bell received his chance to become the Gators' starting quarterback when all of the scholarship quarterbacks ahead of him transferred or were injured prior to the start of the 1984 season, and finally became the primary signal caller when starter Dale Dorminey suffered a serious knee injury in practice just four days before the season opener against the defending national champion Miami Hurricanes. Behind the Gators' outstanding offensive line, memorably dubbed "The Great Wall of Florida," and which included Phil Bromley, Lomas Brown, Billy Hinson, Crawford Ker and Jeff Zimmerman, and supported by fullbackJohn L. Williams, halfbackNeal Anderson and wide receiverRicky Nattiel, Bell made the most of his opportunity and led the Gators to a 9–1–1 seasons in 1984, an SEC championship, and a top-5 national ranking. However, due to NCAA infractions committed under coach Charley Pell, the Gators' were ineligible for bowl consideration and their SEC championship was vacated months later. In 1985, now with a full scholarship, Bell led the Gators to a second consecutive 9-1-1 record. The Gators also finished with best-in-the-conference records of 5–0–1 and 5–1 in 1984 and 1985 and held their first ever #1 ranking in the AP poll during the season. Due to mainly to the effects of ongoing NCAA probations, the Gators' record slipped to 6-5 in 1986 and 1987, Bell's junior and senior seasons. A highlight of those campaigns was Florida's upset of the #5 and undefeated Auburn Tigers in November 1986. Bell had injured his knee the previous week and did not start the game. But with the Gators trailing 17-0 in the 4th quarter, he entered the contest wearing a large knee brace and led his team to a dramatic 18-17 comeback win, capped with a last-minute TD pass to Ricky Nattiel followed by Bell himself "hobbling" into the endzone for a successful 2-point conversion.
In 1996, Bell landed a roster spot with the Indianapolis Colts of the NFL, and in week 15 he entered the game against the Philadelphia Eagles. Bell attempted five passes and completed all of them, throwing for 75 yards and a touchdown on the day. He never again threw a pass in a regular season NFL game, leaving him with the highest career passer rating of any quarterback in NFL history.
Bell's coaching career started in 1990, a year in which he was sidelined from his playing career while recovering from a knee injury. Bell spent the 1990 football season as a graduate assistant coach under Steve Spurrier in Spurrier's first season as head coach at the University of Florida. He resumed his playing career in 1991 and returned to coaching after retiring as an active player. Bell became the offensive coordinator for the Toronto Argonauts in 2001. Afterward, he accepted a job as the head football coach of Trinity Catholic High School in Ocala, Florida. After Trinity Catholic won the 2006 Florida 2B state high school football championship, Bell was hired as head coach of the Jacksonville University football program in 2007. In 2008, he was recognized as the Pioneer Football League Coach of the Year and a finalist for the Eddie Robinson Award after his Dolphins went 9–4 and won the league's championship.