2021 Ostrava Challenger – Singles

Aslan Karatsev was the defending champion but chose not to defend his title.

Benjamin Bonzi won the title after defeating Renzo Olivo 6–4, 6–4 in the final.

Seeds
• # 🇫🇷 Grégoire Barrère (second round)

• # 🇧🇷 Thiago Seyboth Wild (first round)

• # 🇫🇷 Benjamin Bonzi (champion)

• # 🇫🇷 Arthur Rinderknech (semifinals, retired)

• # 🇦🇺 Marc Polmans (quarterfinals)

• # 🇺🇸 Maxime Cressy (first round)

• # Alejandro Tabilo (second round)

• # 🇪🇬 Mohamed Safwat (first round)