| Date: | 12 – 18 July |
| Surface: | Clay / outdoor |
| Location: | Amersfoort, Netherlands |
| Champs: | Tallon Griekspoor |
| Champd: | Luca Castelnuovo /  Manuel Guinard |
| Main Name: | Dutch Open (tennis) |
| Before Year: | 2019 |
| After Name: | Dutch Open (tennis) |
The 2021 Dutch Open, also known by its sponsored name Van Mossel Kia Dutch Open, was a professional tennis tournament played on clay courts. It was the second edition of the Challenger tournament which was part of the 2021 ATP Challenger Tour. It took place in Amersfoort, Netherlands between 12 and 18 July 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Tallon Griekspoor | 124 | 1 | ||
| Botic van de Zandschulp | 139 | 2 | ||
 Australia | Marc Polmans | 154 | 3 | |
| France | Antoine Hoang | 156 | 4 | |
 Egypt | Mohamed Safwat | 170 | 5 | |
 Belgium | Kimmer Coppejans | 191 | 6 | |
 Argentina | Guido Andreozzi | 203 | 7 | |
 Czech Republic | Lukáš Rosol | 204 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry into the singles main draw as alternates:
The following players received entry from the qualifying draw:
Michael GeertsSee main article: 2021 Dutch Open – Singles.
See main article: 2021 Dutch Open – Doubles.
Manuel Guinard def. 
Sergio Galdós / Gonçalo Oliveira 0–6, 6–4, [11–9].