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, 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.

Max Verstappen of Red Bull Racing-Honda won the Drivers' Championship for the first time in his career, having claimed 10 race wins across the season. Verstappen became the first-ever driver from the Netherlands, the first Honda-powered driver since Ayrton Senna in 1991, the first Red Bull driver since Sebastian Vettel in 2013 and the first non-Mercedes driver in the turbo-hybrid era to win the World Championship.

Honda became the second engine supplier in the turbo-hybrid era to power a championship-winning car, after Mercedes. Four-time defending and seven-time champion Lewis Hamilton of Mercedes finished runner-up. Mercedes retained the Constructors' Championship for the eighth consecutive season.

The season featured a close year-long battle for the title between Verstappen and Hamilton, with BBC Sport's Andrew Benson describing it as "one of the most intense, hard-fought battles in sporting history". The two drivers exchanged the championship lead multiple times during the season, and the title contenders were involved in major collisions at the British, Hungarian and Italian Grands Prix. Both drivers entered the season-ending Abu Dhabi Grand Prix tied on points, which ended with a controversial finish, as it was deemed that race control did not handle a late safety car period fully according to the regulations. Verstappen overtook Hamilton in a late restart, after which Mercedes initially protested the results, and later decided not to appeal after their protest was denied. A review of the incident led to key structural changes to race control, including the removal of Michael Masi from his role as race director and the implementation of a virtual race control room, who assist the race director.

This was the first season since 2008 where the champion driver was not from the team that took the constructors' title. The season was also the final season in the sport for 2007 World Champion Kimi Räikkönen.