2019 Challenger Banque Nationale de Gatineau – Men's singles

Bradley Klahn was the defending champion but chose not to defend his title.

Jason Kubler won the title after defeating Enzo Couacaud 6–4, 6–4 in the final.

Seeds
All seeds receive a bye into the second round. • # 🇫🇷 Antoine Hoang (second round)

• # 🇰🇷 Kwon Soon-woo (third round)

• # 🇨🇦 Peter Polansky (third round)

• # 🇺🇸 Michael Mmoh (third round)

• # 🇮🇱 Dudi Sela (third round)

• # 🇸🇰 Norbert Gombos (quarterfinals)

• # Mikael Torpegaard (second round)

• # 🇯🇵 Yasutaka Uchiyama (third round)

• # 🇨🇦 Vasek Pospisil (withdrew)

• # 🇦🇺 Jason Kubler (champion)

• # 🇦🇺 Marc Polmans (quarterfinals)

• # Darian King (semifinals)

• # 🇫🇷 Maxime Janvier (quarterfinals)

• # 🇦🇺 Thanasi Kokkinakis (withdrew)

• # 🇫🇷 Enzo Couacaud (final)

• # 🇰🇷 Lee Duck-hee (quarterfinals)