The 2021 4 Hours of Red Bull Ring was an endurance sportscar racing event held on 16 May, 2021, at Red Bull Ring. It was the second round of the 2021 European Le Mans Series, and the seventh running of the event as part of the European Le Mans Series.
The entry list was revealed on 7 May 2021, and saw 41 entries: 16 in LMP2, 16 in LMP3 and 9 in LMGTE.
Class winners are marked in bold and .