Born and raised in São Paulo, Senna began competitive kart racing at age 13. His first go-kart was built by his father using a lawnmower engine. After twice finishing runner-up at the Karting World Championship, Senna progressed to Formula Ford in 1981, dominating the British and European championships in his debut seasons. He then won the 1983 British Formula Three Championship and the Macau Grand Prix that year.
Senna was born into a wealthy Brazilian family, the middle child of landowner and factory owner Milton Guirado da Silva and his wife Neide Joanna Senna da Silva. He was of Italian, Spanish, and Portuguese descent. His maternal grandfather, João Senna, owned the house where Senna spent his first four years, located near Campo de Marte. Senna was highly athletic and developed an interest in cars and motor racing by the age of four. He attended the Colégio Rio Branco in São Paulo and later enrolled in a college specializing in business administration, but dropped out after three months.
Senna was a devout Catholic. He often read the Bible on long flights from São Paulo to Europe. He once stated, "Just because I believe in God, just because I have faith in God, it doesn't mean that I'm immune. It doesn't mean that I'm immortal." According to his sister, Viviane, on the morning of his death, Senna woke, opened his Bible, and read a text that he would receive "the greatest gift of all, which was God himself."
Senna signed for Toleman in 1984, making his Formula One debut at the Brazilian Grand Prix. After scoring several podium finishes in his rookie season, Senna moved to Lotus in 1985, taking his maiden pole position and victory at the rain-affected Portuguese Grand Prix. He remained at Lotus for his 1986 and 1987 campaigns, scoring multiple wins and finishing third in the World Drivers' Championship in the latter year.
In 1988, Senna joined McLaren to partner Alain Prost. Together, they won 15 of 16 Grands Prix in the dominant McLaren MP4/4. Senna secured his first World Championship by three points, winning eight Grands Prix, a new record at the time. His 13 pole positions also surpassed the previous record. The intense rivalry between Senna and Prost culminated in collisions, notably at Suzuka in 1989 and 1990. In 1990, after a collision at the start of the Japanese Grand Prix, Senna secured his second world title. Prost believed Senna's actions were intentional. A year later, Senna admitted that he intentionally caused the collision as payback for 1989 and his anger over FIA decisions. He later apologized to pundit and former champion Jackie Stewart for his remarks in 1989, telling him that "God won't allow me to live this lie."
In 1991, Senna became the youngest ever three-time world champion, taking seven wins. Despite a challenging season with a new Honda engine, Senna secured the title in Japan. In 1992, Williams's technologically advanced FW14B dominated, and Senna finished fourth overall. He won three races, including Monaco, Hungary, and Italy. Relations between Senna and Michael Schumacher became strained, with Schumacher accusing Senna of "playing around" and colliding with him. Senna also grew concerned about driver safety, notably assisting Érik Comas after a crash at the Belgian Grand Prix.
In 1993, Senna reluctantly re-signed with McLaren on a race-by-race basis, reportedly receiving a salary of $1 million per race. Despite Williams' superiority, Senna won three races, including his second Brazilian Grand Prix and a remarkable performance at the European Grand Prix at Donington Park. He also secured his record-breaking sixth Monaco Grand Prix victory. Senna finished runner-up to Prost in the championship. In mid-October, Senna signed with Williams to replace the retiring Prost for the 1994 season.
With Prost out of the picture, Senna joined Williams for 1994. He expressed a "very negative feeling" about the FW16, anticipating a season with many accidents and stating, "I'll risk saying that we'll be lucky if something really serious doesn't happen." Senna took pole position in the first three races but retired from each. At Imola, he secured pole position again but fatally crashed on lap 7 of the San Marino Grand Prix while leading the race.
The 1994 San Marino Grand Prix was marked by a series of accidents, including the death of Roland Ratzenberger during qualifying. Senna was deeply disturbed by these crashes. On the morning of the race, he spoke with the now-retired Alain Prost about re-establishing the Grand Prix Drivers' Association to organize for driver safety. Senna confided to Prost that "I'm not optimistic at all about this race."
Senna was airlifted to Bologna's Maggiore Hospital, where he was pronounced dead at 18:40 CEST (16:40 GMT). The official time of death under Italian law was 14:17 CEST (12:17 GMT), the time of the crash. The hospital's head of emergency medicine, Dr. Maria Teresa Fiandri, stated that Senna sustained fatal skull fractures, brain injuries, and a ruptured temporal artery. An analysis of the crash primarily focused on Senna's steering column, which broke during the crash. Following the race, legal proceedings were initiated, and a court in 2005 found that the steering column was poorly modified and that its breakage on track caused Senna's accident.
Senna's body was flown back to Brazil on May 4, 1994, and lay in state at the Legislative Assembly building in São Paulo. His funeral took place the following day, May 5. It was estimated that the ceremony and procession were attended by more than a million people, with over 200,000 visitors paying their respects inside the legislative assembly building, making it 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 in São Paulo. His grave bears the epitaph "Nada pode me separar do amor de Deus" (Romans 8:38–39, "Nothing can separate me from the love of God").
In honor of Senna and Ratzenberger, the first two grid positions were left empty at the following race in Monaco, painted with the colors of the Brazilian and Austrian flags. Throughout the rest of the 1994 season, Senna was widely commemorated. The Brazil national football team dedicated their World Cup victory to him in July 1994, holding a banner that read "Senna... Aceleramos juntos, o tetra é nosso!" (lit. 'Senna... We speed together, the fourth title is ours!').
Senna achieved 41 wins, 65 pole positions, 19 fastest laps, and 80 podiums in Formula One. He is remembered for his raw speed, uncompromising driving style, and philanthropy. He is frequently cited as a national hero of Brazil and is acclaimed for his wet-weather performances. Senna was inducted into the International Motorsports Hall of Fame in 2000 and the Automotive Hall of Fame in 2025.
Senna secretly donated millions of U.S. dollars to help poor children. Shortly before his death, he created the framework for an organization dedicated to Brazilian children, which later became the Instituto Ayrton Senna (IAS). The IAS has invested nearly US$80 million over a twelve-year period in social programs and actions in partnership with schools, government, NGOs, and the private sector, aimed at offering children and teenagers from low-income backgrounds the skills and opportunities they need to develop their full potential. Frank Williams, in a 1994 interview, said that "If you want a summary of Ayrton Senna ... he was actually a greater man out of the car than in it."