Mansell funded his early career by selling personal belongings after resigning from his job as an aerospace engineer. He won the 1977 British Formula Ford 1600 championship despite suffering a broken neck in a qualifying accident at Brands Hatch — he discharged himself from hospital and returned to racing. Formula Three followed in 1978 through 1980, during which a collision left him with broken vertebrae. His talent was noticed by Lotus team principal Colin Chapman, who invited him to test at Paul Ricard; the seat went to Elio de Angelis, but Mansell was retained as a test driver.
Mansell's four full seasons at Lotus from 1981 to 1984 were a struggle against unreliable cars and a difficult relationship with team management after Chapman's death in 1982. He was consistently out-performed by de Angelis in the championship standings but showed occasional flashes: he moved from sixteenth to second before retiring at the 1983 British Grand Prix in the turbocharged Lotus 94T, and at the 1984 Monaco Grand Prix briefly passed Alain Prost in the wet. At the 1984 Dallas Grand Prix he collapsed while pushing his car to the finish in extreme heat after leading half the race from pole, a defining image of his perseverance. He left Lotus at the end of 1984 for Williams.
At Williams in 1985 Mansell achieved his first two Formula One victories: the European Grand Prix at Brands Hatch and the South African Grand Prix at Kyalami. These results transformed him into a genuine star in Britain, where his hard-charging, never-give-up style resonated with the public.
In 1986, paired with Nelson Piquet and powered by Honda turbos, Mansell won five races and led the championship for much of the year. The title went to the last round in Adelaide, where a tyre explosion on the main straight with nineteen laps remaining ended his chances as he fought to control the car and avoid the wall. Alain Prost won the championship by two points. Mansell was voted BBC Sports Personality of the Year.
Six more wins followed in 1987, including an iconic British Grand Prix at Silverstone where he recovered from twenty-eight seconds behind to beat Piquet, only for the car to run out of fuel on the slowing-down lap. A qualifying accident at Suzuka injured his back and forced him to miss the final two races; Piquet claimed the championship by default. After a dismal 1988 with the underpowered Judd V8, Mansell joined Ferrari for 1989.
The Italian public dubbed Mansell "il leone" for his fearless style. He won on his Ferrari debut in Brazil — the first Ferrari debut win since Mario Andretti in 1971 — and added a win in Hungary by charging from twelfth on the grid to overtake Ayrton Senna for the lead. He left after 1990, his relationship with new teammate Alain Prost undermined by a car swap incident at the British Grand Prix that Mansell regarded as betrayal.
Mansell's return to Williams in 1991 opened with five wins and a close championship battle, but Senna's consistency and several Mansell retirements left him second overall. The 1992 season saw him and the Williams FW14B dominate the sport to an unprecedented degree. He started with five consecutive victories, set a then-record fourteen pole positions from sixteen races, and sealed the championship at the Hungarian Grand Prix — the eleventh round. His nine wins in a single season and his record qualifying performance were not surpassed until Michael Schumacher's campaigns in 2002 and 2004 respectively.
A public dispute over terms with Williams, and the impending arrival of Prost as teammate, led Mansell to announce his departure at the end of 1992.
Mansell joined Newman/Haas Racing in the American CART series in 1993, partnering Mario Andretti. He became the first "rookie" to take pole and win the season opener at Surfers Paradise. A back injury at Phoenix slowed his start but he recovered to win five races, including one on his fortieth birthday at New Hampshire. He won the CART championship at his first attempt, becoming the only driver in history to hold the Formula One and American open-wheel titles simultaneously.
Mansell returned to Williams for four races in 1994 following Ayrton Senna's fatal accident at Imola. He took the final Grand Prix win of his career at Adelaide — the last race of the season and the last win by a driver over forty in Formula One until 2026. A brief, unsuccessful stint at McLaren in 1995, cut short after two races when he and the car proved incompatible, ended his time at the top level.
Mansell's thirty-one race wins, four runner-up championship finishes before his title, and the 1992 season's near-perfect execution place him among the most accomplished drivers of the turbo and immediately post-turbo eras. He won the BBC Sports Personality of the Year twice, in 1986 and 1992. Turn 17 at the Autodromo Hermanos Rodriguez in Mexico was renamed in his honour in 2015. He was inducted into the International Motorsports Hall of Fame in 2005 and appointed CBE in the 2012 New Year Honours.