2021 Brest Challenger – Singles

Ugo Humbert was the defending champion but chose not to defend his title.

Brandon Nakashima won the title after defeating João Sousa 6–3, 6–3 in the final.

Seeds
• # 🇫🇷 Arthur Rinderknech (first round)

• # 🇺🇸 Jenson Brooksby (withdrew)

• # 🇫🇷 Richard Gasquet (quarterfinals, withdrew)

• # 🇺🇸 Brandon Nakashima (champion)

• # 🇮🇹 Stefano Travaglia (second round)

• # 🇫🇷 Pierre-Hugues Herbert (first round)

• # Henri Laaksonen (quarterfinals)

• # 🇫🇷 Hugo Gaston (second round)