The 1991 Formula One season was the 45th season of FIA Formula One motor racing. It featured the 1991 FIA Formula One World Championship, which commenced on 10 March 1991 and ended on 3 November after sixteen races. Ayrton Senna won his third and final World Drivers' Championship, and McLaren-Honda won the World Constructors' Championship.
The 1991 Formula One season began with the United States Grand Prix in Phoenix, where Ayrton Senna driving for McLaren-Honda took the first victory of the season.
Ayrton Senna claimed a dominant victory at the Monaco Grand Prix, a race he would win multiple times throughout his career, further extending his championship lead.
Riccardo Patrese driving for Williams-Renault won the Mexican Grand Prix, marking one of the highlights of his Formula One career.
Ayrton Senna won the Hungarian Grand Prix, driving a masterful race to secure crucial points for his championship campaign.
Nigel Mansell driving for Ferrari won the Italian Grand Prix at Monza, sending the passionate Italian tifosi into a frenzy.
Ayrton Senna won the Japanese Grand Prix at Suzuka, securing his third World Drivers' Championship with one race remaining in the season.
The 1991 season concluded with the Australian Grand Prix in Adelaide, which was shortened due to heavy rain. Ayrton Senna won the race, capping off his championship-winning season.
