The 89th 24 Hours of Le Mans was a 24-hour automobile endurance race for teams of three drivers each entering Le Mans Prototype (LMP) and Le Mans Grand Touring Endurance (LMGTE) cars held between 21 and 22 August 2021, at the Circuit de la Sarthe, close to Le Mans, France, before 50,000 spectators. It was the event's 89th edition, as organised by the automotive group, the Automobile Club de l'Ouest (ACO) since 1923. The event, the fourth round of the 2021 FIA World Endurance Championship, was postponed from June to August to increase the likelihood of admitting spectators to the race amidst the COVID-19 pandemic in France. A test day was held a week prior to the event on 15 August.

The Circuit des 24 Heures du Mans, also known as Circuit de la Sarthe located in Le Mans, Sarthe, France, is a semi-permanent motorsport race course, chiefly known as the venue for the 24 Hours of Le Mans auto race. Comprising private, race-specific sections of track in addition to public roads which remain accessible most of the year, its present configuration is 13.626 km (8.467 mi) long, making it one of the longest circuits in the world. The capacity of the race stadium, where the short Bugatti Circuit is situated, is 100,000. The Musée des 24 Heures du Mans is a motorsport museum located at the main entrance of the venue.