Svitolina wasted no time in the first set and grabbed a quick 5-0 lead before closing the frame out 6-1, and she kept her foot to the floor in the second set and closed out the No. 2 seed easily.
Wozniacki has yet to win a title in 2017, but will once again have the chance to change that after building on her epic quarter-final win over world number one KarolinaPliskova.
Wozniacki appeared relaxed during the breaks, which gave her time to consult with her father and longtime coach Piotr Wozniacki, before she won five straight games and ultimately took the first set.
Svitolina said she was "a little bit tired" after the rain affected her schedule, but is ready for the final. I think my concentration and just my playing has gone up a notch.
Romanian second seed Halep swept past France's Caroline Garcia 6-4 6-2 in the last of the quarter-finals.
"I didn't win, but I think this whole week was a very big personal victory", Stephens said.
Elina Svitolina already has four singles titles to her name this season, including two other Premier 5 events at Rome and Dubai, but she is looking for a first Rogers Cup title. "Yeah, I'm very happy".
"I just tried to stay steady", she said. However, Caroline employed her feet to the extra work of reaching every ball that was humanly possible to reach and slowly, but ever so steadily, wore Pliskova down.
It was. Stephens, who's playing in just her third singles WTA tournament since being off for almost a year due to injury, displayed the hard-hitting and aggressive style she's known for, and when she was on, she nailed corners with winners, hitting 22 in all.
"It has been a really great year", Wozniacki said after improving to 46-15 on the season. "I just kept hanging in there and I thought we both played a really good match".
On Saturday, Wozniacki broke Stephens in the opening game and took the first set in just half an hour. She had a 5-1 lead in the first set, and needed just 30 minutes to win it, and an hour and 24 minutes to take the match.
The world's No. 50 player received treatment after the match and did not speak to reporters.