2021 Open de Rennes – Singles

Arthur Rinderknech was the defending champion but lost in the semifinals to Benjamin Bonzi.

Bonzi won the title after defeating Mats Moraing 7–6(7–3), 7–6(7–3) in the final.

Seeds
• # 🇫🇷 Richard Gasquet (semifinals)

• # 🇫🇷 Arthur Rinderknech (semifinals)

• # 🇫🇷 Benjamin Bonzi (champion)

• # 🇫🇷 Gilles Simon (first round)

• # 🇬🇧 Andy Murray (second round)

• # 🇫🇷 Lucas Pouille (quarterfinals)

• # 🇫🇷 Grégoire Barrère (second round)

• # 🇨🇿 Tomáš Macháč (second round)