| Men's singles | |
|---|---|
| 2018 Challenger Banque Nationale de Gatineau | |
| Champion |  Bradley Klahn |
| Runner-up |  Ugo Humbert |
| Score | 6–3, 7–6(7–5) |
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.
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)| Semifinals | Final | ||||||||||||
| Ugo Humbert | 6 | 6 | |||||||||||
| 7 | Go Soeda | 4 | 1 | ||||||||||
| Ugo Humbert | 3 | 65 | |||||||||||
| 5 | Bradley Klahn | 6 | 77 | ||||||||||
| 5 | Bradley Klahn | 6 | 6 | ||||||||||
| 2 | Jason Kubler | 2 | 3 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | P Polansky | 77 | 67 | 7 | |||||||||||||||||||||||
| Q |  R Rodríguez | 65 | 79 | 5 | 1 | P Polansky | 6 | 7 | |||||||||||||||||||
| WC | Pavel Krainik | 4 | 6 | 6 | WC | P Krainik | 2 | 5 | |||||||||||||||||||
| WC | Samuel Monette | 6 | 4 | 4 | 1 | P Polansky | 77 | 63 | 64 | ||||||||||||||||||
| B Schnur | 3 | 1 | U Humbert | 64 | 77 | 77 | |||||||||||||||||||||
| U Humbert | 6 | 6 | U Humbert | 6 | 6 | ||||||||||||||||||||||
| WC | B Sigouin | 6 | 6 | WC | B Sigouin | 4 | 4 | ||||||||||||||||||||
| 6 | L Broady | 4 | 2 | U Humbert | 6 | 6 | |||||||||||||||||||||
| 4 | T Ito | 77 | 3 | 5 | 7 | G Soeda | 4 | 1 | |||||||||||||||||||
 M Neuchrist | 62 | 6 | 7 | M Neuchrist | 1 | ||||||||||||||||||||||
| Renta Tokuda | 6 | 61 | 6 | R Tokuda | 1r | ||||||||||||||||||||||
| Q |  E Leshem | 4 | 77 | 3 | M Neuchrist | 63 | 3 | ||||||||||||||||||||
| Q | Jacob Grills | 6 | 77 | 7 | G Soeda | 77 | 6 | ||||||||||||||||||||
| A Sarkissian | 3 | 63 | Q | J Grills | 6 | 1 | 4 | ||||||||||||||||||||
| Y Takahashi | 4 | 3 | 7 | G Soeda | 2 | 6 | 6 | ||||||||||||||||||||
| 7 | G Soeda | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 5 | B Klahn | 7 | 77 | ||||||||||||||||||||||||
| B Mousley | 5 | 63 | 5 | B Klahn | 7 | 6 | |||||||||||||||||||||
| Q |  Y-s Chung | 77 | 6 | Q | Y-s Chung | 5 | 4 | ||||||||||||||||||||
| M Krueger | 63 | 4 | 5 | B Klahn | 67 | 6 | 6 | ||||||||||||||||||||
| A Ward | 4 | 63 |  Z Li | 79 | 4 | 3 | |||||||||||||||||||||
| Z Li | 6 | 77 | Z Li | 2 | 6 | 6 | |||||||||||||||||||||
| WC | A Galarneau | 65 | 5 | 3 | D King | 6 | 4 | 0 | |||||||||||||||||||
| 3 | D King | 77 | 7 | 5 | B Klahn | 6 | 6 | ||||||||||||||||||||
| 8 | F Peliwo | 6 | 4 | 5 | 2 | J Kubler | 2 | 3 | |||||||||||||||||||
| E Escobedo | 3 | 6 | 7 | E Escobedo | 6 | 3 | 77 | ||||||||||||||||||||
 J Menezes | 6 | 6 | J Menezes | 2 | 6 | 65 | |||||||||||||||||||||
| L Miedler | 3 | 3 | E Escobedo | 64 | 77 | 3 | |||||||||||||||||||||
 L Grigelis | 6 | 7 | 2 | J Kubler | 77 | 63 | 6 | ||||||||||||||||||||
 S Napolitano | 2 | 5 | L Grigelis | 65 | 6 | 4 | |||||||||||||||||||||
| K Uchida | 1 | 2 | 2 | J Kubler | 77 | 4 | 6 | ||||||||||||||||||||
| 2 | J Kubler | 6 | 6 | ||||||||||||||||||||||||
Ričardas Berankis was the defending champion but, no longer competing in junior tennis, did not defend his title.
Juan Mónaco was the defending champion, but lost to John Isner in the semifinals.
Isner went on to win the title, defeating Nicolás Almagro in the final, 6–3, 7–5.
Johan Brunström and Izak van der Merwe were the defending champions but van der Merwe decided not to participate.
Brunström paired up with Eric Butorac, but they lost to Steve Johnson and Bradley Klahn in the first round.
Ilija Bozoljac and Somdev Devvarman defeated Johnson and Klahn in the final 6–7(5–7), 7–6(7–3), [11–9] to win the title.
Michael Yani was the defending champion but decided not to participate. Alex Kuznetsov won the title defeating Bradley Klahn in the final.
Austin Krajicek and John Peers were the defending champions, but Peers chose not to compete.
Krajicek paired with Mitchell Krueger but lost in the semifinals to eventual finalists Bradley Klahn and Michael Venus.
Frank Dancevic and Peter Polansky won the title 7–5, 6–3.
Jack Sock was the defending champion but decided to participate at the 2013 Shanghai Rolex Masters instead.
Peter Polansky won the title over 3rd seed Matthew Ebden 7–5, 6–3 to win his first Challenger title.
David Ferrer was the three-time defending champion, but lost in the semifinals to Lu Yen-hsun.
Go Soeda was the two-time defending champion but chose not to compete.
Matthew Barton was the defending champion, but lost in the quarterfinal to Hiroki Moriya.
Bradley Klahn and Michael Venus were the defending champions, but Venus chose to compete in the ATP World Tour. Bradley Klahn played alongside Jordan Thompson and they lost in the semifinals.
Yuki Bhambri was the defending champion, but he did not participate that year.
Bradley Klahn won the title, defeating Jarmere Jenkins in the final, 7–6(7–5), 6–1.
Bradley Klahn was the defending champion, but lost in the semifinals to Jared Donaldson.
Bradley Klahn and Jackson Withrow were the defending champions but only Klahn chose to defend his title, partnering Robert Galloway. Klahn successfully defended his title.
Cameron Norrie was the defending champion but chose not to defend his title.
Marin Čilić was the defending champion, but lost in the second round to Diego Schwartzman.
Evgeny Karlovskiy was the defending champion but lost in the first round to Stefan Kozlov.
Steve Johnson was the defending champion, but lost in the first round to Christopher Eubanks.
Defending champion Rafael Nadal defeated Daniil Medvedev in the final, 6–3, 6–0 to win the men's singles tennis title at the 2019 Canadian Open. It was the first time Nadal successfully defended a hard court title.
Bernard Tomic was the defending champion, but retired in the first round of the qualifying tournament against Denis Istomin.
Reilly Opelka was the defending champion, but lost to Jason Jung in the quarterfinals.