The 1989 FIA Formula One World Championship was the 43rd season of FIA Formula One motor racing. It began on 26 March and ended on 5 November. Alain Prost won his third Drivers' Championship, and McLaren won the Constructors' Championship.

The Drivers' Championship was decided in controversial circumstances at the penultimate race of the season in Japan, when Prost and teammate Ayrton Senna, who needed to win the race, collided in the closing laps. Prost retired while Senna rejoined the track after a push start and crossed the line first, only to be disqualified for not rejoining the track correctly. This handed Prost the title, his last with McLaren before joining Ferrari for 1990.

The season also saw an unprecedented number of entries with 21 constructors originally entered, fielding a total of 40 cars. However, FIRST Racing withdrew from the championship before the opening race, leaving 20 constructors fielding a total of 39 cars, which remains the highest entry in the modern era.