Mansell was born on 8 August 1953 in Upton-upon-Severn, Worcestershire, where his parents, Eric and Joyce Mansell, ran a tea shop. He grew up in Hall Green, Birmingham, and attended Hall Green Secondary school.
Mansell began racing using his own money, achieving success in kart racing before moving to Formula Ford, to the disapproval of his father. In 1976, he won six of the nine races he entered, including his debut at Mallory Park, and in 1977 he became the British Formula Ford 1600 champion, winning 33 of 42 races. During a qualifying session at Brands Hatch in 1977, he broke his neck, narrowly avoiding quadriplegia, and was told he would be confined for six months and unable to drive again. He discharged himself from hospital and returned to racing within three weeks, having previously sold most of his belongings to finance his foray into Formula Ford.
He progressed to Formula Three, racing from 1978 to 1980. His first season saw a pole position and a second-place finish, but the car was hampered by a commercial deal requiring the use of Triumph Dolomite engines, which were vastly inferior to the Toyota engines used by leading teams. He joined David Price Racing for the following season, achieving his first win at Silverstone and finishing eighth in the championship. A collision with Andrea de Cesaris resulted in a crash at Brands Hatch, leaving him with broken vertebrae.
Colin Chapman, owner of Lotus, invited Mansell for a tryout at Paul Ricard, and selected him as a test driver for the 1980 season. He made his Formula One debut at the 1980 Austrian Grand Prix, suffering a fuel leak that caused first and second-degree burns. An engine failure forced his retirement from that race and his second, while an accident at Imola meant he failed to qualify.
Mansell became a full-time Lotus driver in 1981, despite initial reservations from sponsor David Thieme. He achieved a best finish of third place five times during his four years with Lotus. In 1982, Chapman paid Mansell £10,000 not to participate in the 24 Hours of Le Mans, believing the risk was too great. Chapman extended Mansell’s contract to the end of 1984, making him a millionaire. Mansell was deeply affected by Chapman’s sudden death in 1982, stating that "part of me died with him."
In 1984, Mansell finished in the championship top ten for the first time and took his first career pole position. At the Dallas Grand Prix, he pushed his car to the finish line after a transmission failure in extreme heat, salvaging a sixth-place finish. He then announced he would be joining Williams for the 1985 season.
In 1985, Mansell joined Williams alongside Keke Rosberg. He won his first race at the European Grand Prix at Brands Hatch, and followed it with a victory in South Africa. A crash during practice for the French Grand Prix at Paul Ricard resulted in a concussion. In 1986, he won five races, including a close finish at the Spanish Grand Prix, finishing just 0.014 seconds behind Ayrton Senna. The championship went down to the wire in Australia, where a tyre explosion cost him the title, with Alain Prost winning the championship.
Mansell continued with Williams in 1987, winning six races, but a serious qualifying accident at Suzuka injured his back and forced him to miss the final two races. In 1988, Williams used a new, unreliable active suspension system, and Mansell completed only two races.
Mansell moved to Ferrari in 1989, winning the Brazilian Grand Prix in his first race for the team. He won again at the Hungarian Grand Prix, but the season was hampered by gearbox issues. In 1990, he won only one race, and announced his retirement from Formula One at the end of the season.
He returned to Williams in 1991, winning five races and finishing second in the championship. In 1992, he won the first five races of the season and secured the World Drivers' Championship at the Hungarian Grand Prix. He also set a record for the most pole positions in a single season (14), which stood until 2011.
After winning the championship, Mansell left Williams, citing a dispute over a contract. He then moved to CART in 1993, winning the IndyCar World Series in his debut season with Newman/Haas Racing. He won five races in 1993, including a victory at New Hampshire International Speedway on his 40th birthday.
Mansell briefly returned to Formula One with Williams in 1994, winning the Australian Grand Prix, but retired again at the end of the season. He then drove for McLaren in 1995, but retired after just two races due to the car’s handling.
Mansell later competed in the British Touring Car Championship in 1998, achieving a fifth-place finish at Silverstone. He also participated in the Grand Prix Masters series, winning the championship in 2005, and made appearances in sports car racing, including the 24 Hours of Le Mans in 2010 with his sons Leo and Greg.
Mansell has authored several autobiographies, including My Story (1995). He was awarded the BBC Sports Personality of the Year in 1986 and 1992, and inducted into the International Motorsports Hall of Fame in 2005. Turn 17 of the Autodromo Hermanos Rodríguez was renamed in his honour in 2015.