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