The 2021 Biella Challenger Indoor II was a professional tennis tournament played on hard courts. It was the 2nd edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Biella, Italy between 15 and 21 February 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Spain | Alejandro Davidovich Fokina | 54 | 1 | |
| Sebastian Korda | 88 | 2 | ||
 Korea, Republic of | Kwon Soon-woo | 97 | 3 | |
 Italy | Andreas Seppi | 108 | 4 | |
 Poland | Kamil Majchrzak | 109 | 5 | |
 France | Antoine Hoang | 119 | 6 | |
| Italy | Lorenzo Musetti | 122 | 7 | |
 Russian Federation | Evgeny Donskoy | 123 | 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 player received entry as a lucky loser:
See main article: 2021 Biella Challenger Indoor II – Singles.
Kwon Soon-woo def. Lorenzo Musetti 6–2, 6–3.See main article: 2021 Biella Challenger Indoor II – Doubles.
Lloyd Glasspool / 
Harri Heliövaara 7–6(7–4), 6–3.
