| Date: | 20–26 September |
| Edition: | 1st |
| Surface: | Hard (Indoor) |
| Location: | Biel/Bienne, Switzerland |
| Champs: |  Liam Broady |
| Champd: |  Ruben Bemelmans / Daniel Masur |
The 2021 Challenger Biel/Bienne was a professional tennis tournament played on indoor hard courts. It was the 1st edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Biel/Bienne, Switzerland between 20 and 26 September 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 France | ||||
| Henri Laaksonen | 119 | 2 | ||
 Austria | Dennis Novak | 121 | 3 | |
 Czech Republic | Tomáš Macháč | 143 | 4 | |
| United Kingdom | Liam Broady | 145 | 5 | |
| João Sousa | 150 | 6 | ||
| Marc-Andrea Hüsler | 160 | 7 | ||
 Turkey | Cem İlkel | 176 | 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:
The following player received entry as a lucky loser:
See main article: 2021 Challenger Biel/Bienne – Singles.
Liam Broady def. Marc-Andrea Hüsler 7–5, 6–3.See main article: 2021 Challenger Biel/Bienne – Doubles.
Ruben Bemelmans / Daniel Masur def. Marc-Andrea Hüsler / Dominic Stricker Walkover.
