The 2020–21 Gallagher Premiership was the 34th season of the top flight English domestic rugby union competition and the third one to be sponsored by Gallagher. The reigning champions entering the season were Exeter Chiefs, who had claimed their second title after defeating Wasps in the 2020 final. Newcastle Falcons had been promoted as champions from the 2019–20 RFU Championship at the first attempt.

The competition was broadcast by BT Sport for the eighth successive season and with five games also simulcast free-to-air on Channel 5. Highlights of each weekend's games were shown on Channel 5 for the final time, with extended highlights on BT Sport.

Harlequins won their second title after defeating Exeter Chiefs in the final at Twickenham after having finished fourth in the regular season table. No team was relegated this season after a moratorium was agreed.

Due to changes to the global rugby calendar implemented this year and the COVID-19 pandemic prolonging the 2019–20 Premiership Rugby season, this edition featured a later start and later finish and would take place over a reduced timeframe of 32 weeks.

The season also featured a two-week break in January due to the suspension of both of the European Professional Club Rugby competitions.

New regulations were introduced this season for games cancelled as a result of the pandemic or otherwise. A brief outline of the new regulations are:

When cancellation is as a result of COVID-19 points will be awarded as follows.

There are also changes to the regulations allowing the Testing Oversight Group to cancel matches.