2021 Challenger de Buenos Aires – Singles

Sumit Nagal was the defending champion but chose not to defend his title.

Sebastián Báez won the title after defeating Thiago Monteiro 6–4, 6–0 in the final.

Seeds
• # 🇧🇷 Thiago Monteiro (final)

• # 🇦🇷 Juan Manuel Cerúndolo (semifinals)

• # 🇦🇷 Francisco Cerúndolo (semifinals)

• # 🇵🇪 Juan Pablo Varillas (quarterfinals)

• # 🇧🇴 Hugo Dellien (quarterfinals)

• # 🇧🇷 Thiago Seyboth Wild (first round)

• # 🇦🇷 Sebastián Báez (champion)

• # 🇦🇷 Tomás Martín Etcheverry (quarterfinals)