Pironi was born in Villecresnes, Val-de-Marne. He is the half-brother and first cousin of racing driver José Dolhem — they shared the same father, and their mothers were sisters. Pironi began studying engineering and earned a science degree before enrolling at the Winfield Racing School at Paul Ricard. He graduated as the school's best student of 1972, earning a scholarship into Formula France, where he became champion in 1974. He subsequently won the Super Renault championship in 1976 and took victory in the Monaco Grand Prix Formula Three support race in 1977. He finished third in the 1977 European Formula Two Championship, setting the stage for a Formula One entry.
Pironi made his Formula One debut with Tyrrell at the Argentine Grand Prix on 15 January 1978. In the same year he was part of Renault's assault on Le Mans, sharing the distinctive "bubble roof" A442B with Jean-Pierre Jaussaud and winning the race by four laps from the rival Porsche 936s.
After two seasons demonstrating consistent pace with the underfinanced Tyrrell team, Pironi moved to Ligier in 1980, partnering Jacques Laffite. He took his maiden Formula One victory at the Belgian Grand Prix at Zolder and recorded several podium finishes during the season, ending fifth in the drivers' standings.
Pironi's performances attracted Enzo Ferrari, who signed him for 1981 as teammate to Gilles Villeneuve. Ferrari later described Pironi's arrival at Maranello as winning "everyone's admiration and affection, not only for his gifts as an athlete, but also for his way of doing things." In his first season with Ferrari, Pironi was consistently slower in qualifying than Villeneuve but steadier across race distances.
The 1982 season brought both Pironi's greatest results and the most contested moments of his career. At the San Marino Grand Prix, with the FOCA teams boycotting the event and only Renault offering genuine opposition, Ferrari's two drivers ran in close formation at the front. The team signalled both cars to slow and hold position, but Pironi passed Villeneuve on the final lap to take the win. Villeneuve, convinced a prior agreement had been broken, was furious and vowed never to speak to Pironi again. Two weeks later at the Belgian Grand Prix, Villeneuve was killed in qualifying, an event widely linked to his determination to beat Pironi's lap time. The shadow of Zolder followed Pironi through the remainder of the season.
By mid-season Pironi led the World Drivers' Championship with 39 points, ahead of John Watson and Keke Rosberg. At the German Grand Prix at Hockenheim, during wet untimed practice, Pironi was running a new-specification Goodyear rain tyre that was lapping significantly faster than his teammate Patrick Tambay. In the race, visibility in the spray was severely compromised by the ground-effect cars' aerodynamics. Pironi drove into the back of Alain Prost's invisible Renault at high speed, sustaining multiple severe fractures to both legs. He never returned to Formula One. Missing four of the season's fourteen races, Pironi lost the title to Keke Rosberg by five points. Across his Formula One career he won three races, took four pole positions, five fastest laps, and 13 podiums, scoring 101 championship points.
In 1986, with both legs recovered sufficiently for him to walk unaided, Pironi tested for the AGS team at Paul Ricard and subsequently drove the Ligier JS27 at Dijon-Prenois, proving he retained competitive pace. A return to Formula One was complicated by the terms of his insurance payout, which was predicated on sustaining career-ending injuries; it was believed an arrangement with his insurer had been reached for a 1988 comeback with the Larrousse & Calmels team.
Unable to return to Formula One immediately, Pironi turned to offshore powerboat racing. On 23 August 1987 he was killed in the Needles Trophy Race near the Isle of Wight. His boat, Colibri 4, rode over a wave generated by the Esso Avon oil tanker and flipped. Pironi and his two crew members — journalist Bernard Giroux and his friend Jean-Claude Guénard — all died. Their deaths were recorded at Newport, Isle of Wight.
After Pironi's death, his girlfriend Catherine Goux gave birth to twin sons. In honour of both Pironi and Gilles Villeneuve, she named them Didier and Gilles. Gilles Pironi subsequently joined Mercedes AMG Petronas as an engineer and stood on the podium at the 2020 British Grand Prix, receiving the constructors' trophy.
Didier Pironi remains one of the most discussed might-have-been champions in Formula One history. His 1982 title campaign, derailed by the Hockenheim accident while he led the standings, is frequently cited as one of the cruelest reversals in the sport. The controversy of San Marino 1982 and its connection to Villeneuve's death have ensured that the two drivers' intertwined stories continue to be analysed decades later. Pironi was a versatile competitor whose résumé spanned Formula One, Le Mans, the Procar championship, and offshore powerboat racing — excelling at each level until his final, fatal accident at 35.