Osaka, chasing her first WTA Tour-level title since the 2021 Australian Open, needed only 68 minutes to dispatch the Ukrainian star and book a Wednesday semi-final with Danish 16th seed Clara Tauson, who stunned reigning Australian Open champion Madison Keys 6-1, 6-4.
"I'm just having a lot of fun playing. I'm glad to be here," Osaka said. "I think I'll be seeded in the US Open because I won my match. That was a really good goal for me. I'm just really excited."
Osaka seeks her eighth WTA-level title, and her first since a maternity leave comeback last year and her first below the Grand Slams at the WTA level since the 2019 China Open.
Osaka broke for a 3-1 edge in the opening set and exchanged breaks in the last three games to capture the set after 38 minutes, then cruised through the second set, taking the triumph when Svitolina hit a forehand wide.
Tauson dominated the opening set and took full advantage of Keys giving up a break on a double fault to open the second. The Dane won 12 of 19 points on her second serves and kept Keys at bay most of the night.
Tauson dedicated her victory to her late grandfather, who died on Sunday as the Dane was dispatching Polish second seed Iga Swiatek, who won her sixth Grand Slam title last month at Wimbledon.
"Two days ago, my grandfather unfortunately passed away, so I really wanted to win for him today," a tearful Tauson said after beating US sixth seed Keys.
"I was told the day after I beat Iga, so I really wanted to come out and show my best tennis for him. Hopefully he's watching."
Keys joined a scrap heap of Montreal seeds, with the top five seeds and seven of the top 10 seeds ousted before the quarter-finals. Tauson is one win away from her second WTA 1000 final, having lost the first in February at Dubai to Mirra Andreeva.
She seeks her fourth career WTA title after the 2021 Lyon and Luxembourg Opens and this year's Auckland Open, where Osaka retired after winning the first set of the final.
That was Tauson's only meeting with Osaka, while the Dane is 2-0 against Svitolina, winning in three sets on clay in Portugal in 2023 and in a third-set tiebreaker at Dubai six months ago.
Tauson, who also eliminated Polish second seed Iga Swiatek in the fourth round, is one win from her second WTA 1000 final, having lost the first in February at Dubai to Mirra Andreeva.
The Dane dominated Keys in the first set, breaking in the fourth and sixth games, and Keys double-faulted away another break to begin the second set.
Tauson held from there to win, never facing a break point in the second set before holding at love in the last game to end matters after 70 minutes.
Elena Rybakina, the 2022 Wimbledon champion, and 18-year-old Canadian sensation Victoria Mboko will meet in Wednesday's other semi-final on the Montreal hardcourts in the US Open tuneup.
Rybakina won their only prior meeting 6-3, 7-5 last month in the second round at Washington.