The 2021 Queen's Club Championships (also known as the cinch Championships for sponsorship reasons) was a tennis tournament played on outdoor grass courts at the Queen's Club in London, United Kingdom from 14 to 20 June 2021. It was the 118th edition of the event and part of the ATP Tour 500 series of the 2021 ATP Tour.
<sub>*per team</sub>
The following players received wildcards into the main draw:
The following player received entry using a protected ranking:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
The following pairs received wildcards into the doubles main draw:
The following pair received entry as an alternate: