2023 Lisboa Belém Open – Men's singles

Marco Cecchinato was the defending champion but chose not to defend his title.

Flavio Cobolli won the title after defeating Benjamin Hassan 7–5, 7–5 in the final.

Seeds
• # 🇪🇸 Albert Ramos Viñolas (semifinals)

• # 🇮🇹 Flavio Cobolli (champion)

• # 🇰🇿 Timofey Skatov (first round)

• # 🇪🇸 Pablo Llamas Ruiz (second round)

• # Ivan Gakhov (second round)

• # 🇫🇷 Titouan Droguet (first round)

• # 🇨🇿 Zdeněk Kolář (first round)

• # 🇮🇹 Matteo Gigante (first round)