The FIA World Endurance Championship had operated on a winter or extended calendar for the 2019–20 season due to the global pandemic, delaying the 24 Hours of Le Mans and other rounds. The 2021 season restored a conventional annual format, with the calendar compressed to six rounds — down from eight — partly to reduce costs arising from the pandemic's financial impact. The 6 Hours of Silverstone, 6 Hours of Shanghai, and Lone Star Le Mans were removed, while the 6 Hours of Monza was added to the schedule.
The defining change of 2021 was the introduction of the Le Mans Hypercar regulations, replacing the LMP1 class that had underpinned the championship's top tier since its 2012 revival. Under the new rules, manufacturers could build bespoke LMH designs or road-car-derived hypercars, provided that at least twenty road-legal models were produced over a two-year homologation period. Cars were required to weigh a minimum of 1,030 kg, with power capped at 680 hp to target a benchmark lap time of three minutes and thirty seconds at the Circuit de la Sarthe. Hybrid energy-recovery systems were permitted on the front axle only, contributing up to 272 hp of the total power output. A Balance of Performance system — modelled on the GTE class system — was applied to ensure parity between hybrid and non-hybrid machinery.
Non-hybrid LMP1 cars were permitted to participate in the 2021 season under a grandfathering arrangement, easing the transition period as manufacturers prepared their new Hypercar programmes.
In LMP2, power was reduced by 40 horsepower to 560 hp to maintain the performance gap between it and the new top class. A specification Goodyear tyre was introduced in LMP2, ending the tyre competition between Goodyear and Michelin in that class.
Toyota entered the championship with the GR010 Hybrid, a bespoke Hypercar developed from the GR Super Sport Concept, which was launched in January 2021. Scuderia Cameron Glickenhaus entered with its SCG 007 LMH car, developed in partnership with Sauber Motorsport, Joest Racing, and engine specialists Pipo Moteurs. Alpine entered a single rebadged Rebellion R13 LMP1 under the grandfathering provision, operated by Signatech Alpine.
Several manufacturers were conspicuous by their absence. Aston Martin had initially planned to enter a Valkyrie-based Hypercar but placed that programme on hold. Rebellion Racing ended its operations after the prior season. ByKolles Racing Team had announced a hypercar programme but did not appear on the 2021 entry list. Peugeot announced it would join the championship from 2022 onwards.
In LMGTE Pro, Aston Martin Racing ended its factory programme run by Prodrive, redirecting its resources to Formula One and its LMGTE Am effort.
The season opened with a Prologue test at Spa-Francorchamps. The original first round — the 1000 Miles of Sebring scheduled for March 2021 — was cancelled due to the pandemic and replaced by a 1000 Miles of Portimão on 4 April 2021, which was later postponed to June. Spa-Francorchamps consequently became the site of the season's first competitive round. The 24 Hours of Le Mans was moved from its traditional June date to 21–22 August 2021 to allow the possibility of admitting spectators. The 6 Hours of Fuji was cancelled entirely due to Japanese travel restrictions and replaced by an additional event in Bahrain.
The championship awarded five titles across drivers, with two holding World Championship status: the Hypercar World Endurance Drivers' Championship and the GTE World Endurance Drivers' Championship. FIA Endurance Trophies were given in LMP2, LMP2 Pro/Am, and LMGTE Am.
To score championship points, drivers were required to complete the full timed race distance and cover at least 70 percent of the overall winner's race distance. A single bonus point was available to the pole position car in each class per round. For a race's points to count, at least two laps had to be completed under green flag conditions.
The Hypercar Teams' World Endurance Championship awarded points to the highest-finishing car from each team per race. The GTE Manufacturers' Championship credited the two best-finishing cars per manufacturer across both GTE categories.
The 2021 season established the Le Mans Hypercar class as the new pinnacle of the FIA World Endurance Championship, setting the regulatory framework that subsequent manufacturers — including Peugeot, Ferrari, Cadillac, Porsche, and BMW — would adopt in the following seasons. The compressed calendar and cost-reduction measures implemented in 2021 reflected the lasting structural pressures the COVID-19 pandemic imposed on global motorsport, while the Balance of Performance system introduced in the Hypercar class became a defining feature of the top-tier endurance landscape going forward.