The 2021 FIA Formula 3 Championship was a motor racing championship for Formula 3 cars that was sanctioned by the Fédération Internationale de l'Automobile (FIA). The championship was the twelfth season of Formula 3 racing and the third season run under the guise of the FIA Formula 3 Championship, an open-wheel racing category that serves as the third tier of formula racing in the FIA Global Pathway. The category was run in support of selected rounds of the 2021 FIA Formula One World Championship. As the championship was a spec series, all teams and drivers that competed in the championship ran the same car, the Dallara F3 2019. The championship was contested over twenty-one races at seven circuits. It started in May with a round in support of the Spanish Grand Prix and ended in September on the weekend of the Russian Grand Prix.

The 2021 FIA Formula One World Championship was a motor racing championship for Formula One cars which was the 72nd running of the Formula One World Championship. It is recognised by the Fédération Internationale de l'Automobile (FIA), the governing body of international motorsport, as the highest class of competition for open-wheel racing cars. The championship was contested over twenty-two Grands Prix, and held around the world. Drivers and teams competed for the titles of Formula One World Champion Driver and Formula One World Champion Constructor, respectively.