The 2021 Nottingham Open (also known as the Viking Open Nottingham for sponsorship purposes) was a professional tennis tournament played on outdoor grass courts.

It was the 13th edition of the event for women and the 25th edition for men.

It was classified as a WTA 250 on the 2021 WTA Tour for the women, and as an ATP Challenger Tour event for the men.

The event took place at the Nottingham Tennis Centre in Nottingham, United Kingdom from 6 through 13 June 2021.

[1] The following players received wildcards into the main draw: The following players received entry from the qualifying draw: The following players received wildcards into the main draw: The following players received entry from the qualifying draw: The following players received entry as lucky losers: The following pairs received wildcards into the doubles main draw: The following pair received entry using a protected ranking: The following pair received entry as an alternate: