2018 Challenger Banque Nationale de Gatineau – Men's singles

Denis Shapovalov was the defending champion but chose not to defend his title.

Bradley Klahn won the title after defeating Ugo Humbert 6–3, 7–6(7–5) in the final.

Seeds
• # 🇨🇦 Peter Polansky (quarterfinals)

• # 🇦🇺 Jason Kubler (semifinals)

• # Darian King (second round)

• # 🇯🇵 Tatsuma Ito (first round)

• # 🇺🇸 Bradley Klahn (champion)

• # 🇬🇧 Liam Broady (first round)

• # 🇯🇵 Go Soeda (semifinals)

• # 🇨🇦 Filip Peliwo (first round)