| Singles | |
|---|---|
| 2021 Biella Challenger Indoor III | |
| Champion |  Andreas Seppi |
| Runner-up |  Liam Broady |
| Final score | 6–2, 6–1 |
Kwon Soon-woo was the defending champion [1] but chose not to defend his title.
Andreas Seppi won the title after defeating Liam Broady 6–2, 6–1 in the final.
James Duckworth (first round) Andreas Seppi (champion)
Yūichi Sugita (first round) Yasutaka Uchiyama (first round)
Peter Gojowczyk (quarterfinals, retired)
Jurij Rodionov (quarterfinals)
Marc-Andrea Hüsler (first round)
Martin Kližan (first round)| Semifinals | Final | ||||||||||||
 Illya Marchenko | 3 | 62 | |||||||||||
| Liam Broady | 6 | 77 | |||||||||||
| Liam Broady | 2 | 1 | |||||||||||
| 2 | Andreas Seppi | 6 | 6 | ||||||||||
 Robin Haase | 1 | 5 | |||||||||||
| 2 | Andreas Seppi | 6 | 7 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | J Duckworth | 4 | 3 | ||||||||||||||||||||||||
| Q | A Arnaboldi | 6 | 6 | Q | A Arnaboldi | 2 | 5 | ||||||||||||||||||||
 T-l Wu | 4 | 62 | I Marchenko | 6 | 7 | ||||||||||||||||||||||
| I Marchenko | 6 | 77 | I Marchenko | 6 | 6 | ||||||||||||||||||||||
| Q |  J Forejtek | 6 | 6 | Q | J Forejtek | 4 | 1 | ||||||||||||||||||||
| T Kamke | 3 | 3 | Q | J Forejtek | 78 | 6 | |||||||||||||||||||||
| Q | A Santillan | 7 | 3 | 6 | Q | A Santillan | 66 | 3 | |||||||||||||||||||
| 7 | M-A Hüsler | 5 | 6 | 3 | I Marchenko | 3 | 62 | ||||||||||||||||||||
| 3 | Y Sugita | 2 | 2 | L Broady | 6 | 77 | |||||||||||||||||||||
| WC | L Nardi | 6 | 6 | WC | L Nardi | 3 | 4 | ||||||||||||||||||||
| L Broady | 77 | 6 | L Broady | 6 | 6 | ||||||||||||||||||||||
| LL | J Lenz | 61 | 4 | L Broady | 6 | 6 | |||||||||||||||||||||
| Z Kolář | 6 | 77 | 6 | J Rodionov | 4 | 3 | |||||||||||||||||||||
| Y Maden | 2 | 64 | Z Kolář | 2 | 6 | 67 | |||||||||||||||||||||
| A Vukic | 4 | 4 | 6 | J Rodionov | 6 | 4 | 79 | ||||||||||||||||||||
| 6 | J Rodionov | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 8 | M Kližan | 1 | 1 | ||||||||||||||||||||||||
| Q | M Bachinger | 6 | 6 | Q | M Bachinger | 2 | 4 | ||||||||||||||||||||
| D Masur | 77 | 3 | 2 | R Haase | 6 | 6 | |||||||||||||||||||||
| R Haase | 65 | 6 | 6 | R Haase | 6 | 6 | |||||||||||||||||||||
 B Schnur | 6 | 6 | B Schnur | 3 | 4 | ||||||||||||||||||||||
| WC | S Napolitano | 2 | 4 | B Schnur | 6 | 6 | |||||||||||||||||||||
| L Giustino | 7 | 6 | L Giustino | 4 | 2 | ||||||||||||||||||||||
| 4 | Y Uchiyama | 5 | 4 | R Haase | 1 | 5 | |||||||||||||||||||||
| 5 | P Gojowczyk | 65 | 6 | 6 | 2 | A Seppi | 6 | 7 | |||||||||||||||||||
| WC | G Zeppieri | 77 | 0 | 1 | 5 | P Gojowczyk | 65 | 6 | 77 | ||||||||||||||||||
| PR | D Brown | 1 | 4 |  Q Halys | 77 | 1 | 64 | ||||||||||||||||||||
| Q Halys | 6 | 6 | 5 | P Gojowczyk | 1r | ||||||||||||||||||||||
| H Grenier | 4 | 2 | 2 | A Seppi | 3 | ||||||||||||||||||||||
| T Lamasine | 6 | 6 | T Lamasine | 6 | 1 | 64 | |||||||||||||||||||||
| S Stakhovsky | 2 | 4 | 2 | A Seppi | 1 | 6 | 77 | ||||||||||||||||||||
| 2 | A Seppi | 6 | 6 | ||||||||||||||||||||||||
Andreas Seppi was the defending champion, but he lost in the quarterfinals to Robin Haase.
Robin Haase won the title, defeating Albert Montañés 6–4, 4–6, 6–1 in the final.
Novak Djokovic was the defending champion, but decided not to participate.
Andreas Seppi won the title defeating Benoît Paire 6–3, 6–2 in the final.
Jo-Wilfried Tsonga successfully defended his title, defeating Andreas Seppi in the final, 6–1, 6–2.
Roger Federer was the defending champion, but lost in the quarterfinals to Julien Benneteau.
Juan Martín del Potro won the title, defeating Benneteau in the final 7–6(7–2), 6–3.
Andreas Seppi was the defending champion. Seppi defended his title, defeating Matthias Bachinger in the final, 6–4, 6–3.
Roger Federer was the two-time defending champion and successfully defended his title, defeating Andreas Seppi in the final, 7–6(7–1), 6–4.
Viktor Troicki was the defending champion and successfully defended his title, defeating Grigor Dimitrov in the final, 2–6, 6–1, 7–6(9–7).
Taro Daniel was the defending champion but chose not to defend his title.
Yūichi Sugita was the defending champion but chose not to defend his title.
Yasutaka Uchiyama was the defending champion but chose not to defend his title.
Borna Ćorić was the defending champion, but retired from his quarterfinal match against Pierre-Hugues Herbert.
Fabio Fognini was the defending champion, but lost in the quarterfinals to Taylor Fritz.
Daniil Medvedev was the defending champion, but chose not to defend his title.
Roger Federer was the two-time defending champion and successfully defended his title, defeating Alex de Minaur in the final, 6–2, 6–2. The victory made Federer the first player in ATP history to win 10 titles on two different surfaces.
Hubert Hurkacz was the defending champion, but chose not to defend his title.
This was the first edition of the tournament.
This was the second of seven editions of the tournament in the 2021 tennis season. Illya Marchenko was the defending champion but lost in the quarterfinals to Andreas Seppi.
Marcos Baghdatis was the defending champion but retired from professional tennis in 2019.
Taylor Fritz was the defending champion from when the event was last held in 2019, but withdrew before the tournament with a knee injury.
John Millman was the defending champion, but lost in the quarterfinals to James Duckworth.