2021 Dutch Open – Singles

Mats Moraing was the defending champion but lost in the second round to Botic van de Zandschulp.

Tallon Griekspoor won the title after defeating van de Zandschulp 6–1, 3–6, 6–1 in the final.

Seeds
• # Tallon Griekspoor (champion)

• # Botic van de Zandschulp (final)

• # 🇦🇺 Marc Polmans (first round)

• # 🇫🇷 Antoine Hoang (semifinals)

• # 🇪🇬 Mohamed Safwat (second round)

• # 🇧🇪 Kimmer Coppejans (quarterfinals)

• # 🇦🇷 Guido Andreozzi (semifinals)

• # 🇨🇿 Lukáš Rosol (quarterfinals)