The 2021 Biella Challenger V was a professional tennis tournament played on outdoor red clay courts. It was part of the 2021 ATP Challenger Tour. It took place in Biella, Italy between 3 and 9 May 2021.

Country	Player	Rank1	Seed
POR	Pedro Sousa	113	1
BOL	Hugo Dellien	125	2
USA	Mackenzie McDonald	127	3
GER	Cedrik-Marcel Stebe	134	4
ITA	Federico Gaio	138	5
FRA	Hugo Gaston	147	6
PER	Juan Pablo Varillas	150	7
JPN	Go Soeda	154	8

• Rankings are as of 26 April 2021.^[1]

The following players received wildcards into the singles main draw:

• Hamad Međedović
• Stefano Napolitano
• Luca Vanni

The following player received entry into the singles main draw using a protected ranking:

• Thanasi Kokkinakis

The following players received entry into the singles main draw as alternates:

• Jay Clarke
• Andrea Collarini
• Aleksandar Vukic

The following players received entry from the qualifying draw:

• Guido Andreozzi
• Viktor Galović
• Maximilian Marterer
• Felipe Meligeni Alves

The following players received entry as lucky losers:

• Marcelo Tomás Barrios Vera
• Dimitar Kuzmanov

• Juan Pablo Varillas def. Guido Andreozzi 6–3, 6–1.

• André Göransson / Nathaniel Lammons def. Rafael Matos / Felipe Meligeni Alves 7–6^(7–3), 6–3.