| Date: | 19–25 July |
| Edition: | 39th |
| Location: | Tampere, Finland |
| Surface: | Clay |
| Champs: |  Jiří Lehečka |
| Champd: |  Pedro Cachin / Facundo Mena |
| Before Year: | 2019 |
The 2021 Tampere Open was a professional tennis tournament played on clay courts. It was the 39th edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Tampere, Finland, on 19–25 July 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Botic van de Zandschulp | 132 | 1 | ||
 France | Antoine Hoang | 148 | 3 | |
 Spain | Mario Vilella Martínez | 178 | 4 | |
 Kazakhstan | Dmitry Popko | 185 | 5 | |
 Belgium | Kimmer Coppejans | 191 | 6 | |
| France | Alexandre Müller | 197 | 7 | |
| Argentina | Guido Andreozzi | 206 | 8 |
The following players received wildcards into the singles main draw:
The following player received entry into the singles main draw as a special exempt:
The following players received entry into the singles main draw as alternates:
The following players received entry from the qualifying draw:
The following players received entry as lucky losers:
See main article: 2021 Tampere Open – Singles.
Jiří Lehečka def. Nicolás Kicker 5–7, 6–4, 6–3.See main article: 2021 Tampere Open – Doubles.
Pedro Cachin / Facundo Mena def. 
Orlando Luz / Felipe Meligeni Alves 7–5, 6–3.
