The 2021 4 Hours of Le Castellet was an endurance sportscar racing event held on 6 June, 2021, at Circuit Paul Ricard. It was the third round of the 2021 European Le Mans Series, and the 13th running of the event as part of the European Le Mans Series.
The entry list was revealed on 2 June 2021, and saw 42 entries: 16 in LMP2, 16 in LMP3, 9 in LMGTE and 1 Innovative car.
Class winners are marked in bold and .