Born in São Paulo on 21 March 1960, Senna began competitive karting at 13, starting his debut race on pole against older opponents. He won the South American Kart Championship in 1977 and finished runner-up at the Karting World Championship in both 1979 and 1980. In 1981 he moved to England, winning the British and Townsend Thoresen Formula Ford 1600 Championships with Van Diemen in his debut season. For 1982 he dominated the British and European Formula Ford Championships, winning 15 of 17 British rounds. He adopted the maternal surname Senna professionally. In 1983 he won the British Formula Three Championship for West Surrey Racing after a close battle with Martin Brundle, and in November took the inaugural Macau Formula Three Grand Prix.
Senna signed with Toleman for his 1984 debut. He produced a famous drive at the rain-affected Monaco Grand Prix, passing Lauda for second and closing rapidly on leader Alain Prost before the race was stopped, and finished ninth in the championship with 13 points.
At Lotus from 1985 to 1987, he took his first pole and first victory at the rain-affected 1985 Portuguese Grand Prix, winning by over a minute. His 1985 season yielded seven poles — more than any other driver — despite the Renault-powered Lotus's unreliability. In 1986 he won the Spanish Grand Prix by 0.014 seconds from Mansell in one of Formula One's closest-ever finishes and also took Detroit. His seven poles and four wins in 1987 included his first Monaco victory; he finished third in the championship before negotiating a move to McLaren.
Senna joined McLaren in 1988 to partner Alain Prost in the Honda-powered MP4/4. Together they won 15 of 16 races, with Senna taking his maiden championship by three points after winning eight Grands Prix — a record at the time. His 13 pole positions also set a new record.
The Senna–Prost rivalry defined the era. At the 1989 Japanese Grand Prix, a title-deciding collision left both cars stopped; Senna restarted, won the race, and was then disqualified for cutting the chicane — handing Prost the title. The following year, with Prost at Ferrari, Senna deliberately collided with him at the first corner of the Japanese Grand Prix to clinch his second championship. Senna secured his third title in 1991 with seven victories including his home race in Brazil. In 1993, driving for McLaren on a race-by-race basis with customer Ford engines, he still won five races, including his record-breaking sixth Monaco Grand Prix victory, surpassing the five held by Graham Hill. At the European Grand Prix at Donington Park in wet and changing conditions he overtook four drivers on the opening lap and lapped all but the runner-up — widely regarded as one of the greatest individual performances in the sport's history.
Senna joined Williams for 1994, replacing the retired Prost. He was immediately concerned by the FIA's ban on electronic driver aids — active suspension, anti-lock brakes, traction control — which stripped capabilities the Williams FW16 had been developed around. He took pole at each of the first three races but retired from all three. On the morning of the San Marino Grand Prix at Imola — already a weekend marked by Barrichello's heavy accident on Friday and Roland Ratzenberger's death in qualifying on Saturday — Senna spoke with Prost about re-forming the Grand Prix Drivers' Association to campaign for safety improvements. He confided that he had a very negative feeling about the race.
On lap 7 of the 1994 San Marino Grand Prix, Senna crashed at the high-speed Tamburello corner and was airlifted to the Maggiore Hospital in Bologna, where he was pronounced dead at 18:40 CEST. He suffered fatal skull fractures, brain injuries, and a ruptured temporal artery. An Austrian flag found in his cockpit was believed intended as a tribute to Ratzenberger.
Investigation centred on the steering column, which broke during the crash. The night before the race, Senna had requested the wheel be adjusted; Williams welded parts to extend the existing column rather than build a new one. Six defendants were charged with manslaughter. Italian courts ultimately found that the poorly modified column had broken and caused the crash; Patrick Head was found culpable but protected by the statute of limitations.
His state funeral in São Paulo on 5 May drew more than a million people, the largest funeral procession in the city's history. The Brazilian government declared three days of national mourning. Senna was buried in the Morumbi Cemetery with the epitaph "Nada pode me separar do amor de Deus" (Nothing can separate me from the love of God).
Senna achieved 41 wins, 65 pole positions, 19 fastest laps, and 80 podiums. He is especially acclaimed for his wet-weather performances — at Monaco in 1984, Portugal in 1985, and Donington Park in 1993 — and as of 2023 retained the highest ratio of wet-race wins among all Formula One drivers. A 2009 Autosport poll of 217 current and former drivers gave him a near-unanimous vote as the greatest of all time; Formula One's 2020 AWS algorithm named him the fastest qualifier of all time. He was inducted into the International Motorsports Hall of Fame in 2000 and the Automotive Hall of Fame in 2025.
His death at Imola triggered sweeping safety reforms: improved barriers, redesigned circuits, raised crash standards, reduced engine power, and overhauled medical procedures. The Tamburello corner was altered in 1995. The 1994 San Marino Grand Prix weekend is widely regarded as the turning point in modern Formula One safety.
Senna is a national hero in Brazil. Statues stand at Imola, Barcelona, Rio de Janeiro, Interlagos, and Donington Park; numerous track sections worldwide bear his name. Lewis Hamilton, Fernando Alonso, Sebastian Vettel, and many other drivers have publicly named him as a formative influence. His philanthropic legacy continues through the Instituto Ayrton Senna, founded by his sister Viviane.