After winning six matches in Montreal, Osaka also moves up in the rankings 24 spots from number 49 to number 25.
This also means that both players will be seeded at the US Open, the final four of four of the grand slams or the most important tournaments in tennis.
The US Open takes place August 24 - September 7 in New York City.
Hitting powerful serves, and groundstrokes, the 27 year old Osaka took set one without ever facing a breakpoint.
However, serving at 2 games all in set two, Osaka doublefaulted before committing several groundstroke errors; some forced from aggressive Mboko forehands.
Mboko won three games in a row to lead 5-2.
Osaka broke serve in the following game after Mboko struck three doublefaults.
Osaka finished the game with a forehand return winner to trail 5-3.
Osaka held serve to reach 5-4 before Mboko resorted to serving slower serves to avoid additional double faults; some serves as slow as 68 miles per hour.
Osaka was unable to capitalize on Mboko's serve speeds as she struck several groundstroke errors to drop the set.
Osaka then left the court to take a bathroom break.
However Osaka was unable to regroup as she at times appeared bothered by the loud Canadian crowd as well as Mboko's slower pace of playing such as going to the towel when Osaka was ready to serve.
At one all in set three, the Japanese player hit a ball up out of the court and received a code violation for ball abuse.
Along with her other problems, Osaka had trouble handling the mix of offense and defense from the Canadian player.
Mboko hit sliced forehands to get back some of Osaka's best most powerful forehands which drew errors from Osaka.
It was not Osaka's day as she hit too many errors and was unable to stop Mboko's Cinderella story in her current home country after two hours and four minutes of play.
Mboko for the week incredibly defeated four grand slam champions: the 2018 and 2020 US Open champion Osaka, the 2020 Australian Open champion Sofia Kenin of the USA, the current Roland Garros champion Coco Gauff of the USA and the 2022 Wimbledon champion Elena Rybokina of Kazakhstan.