Stosur, the third-seeded Australian, brushed aside sixth-seeded American Madison Keys 6-1 6-2 in little more than an hour.
Canadian Bouchard is the fifth seed and she was a convincing 6-2 6-2 winner over South Korean wildcard Kurumi Nara to reach her first WTA final.
Stosur was clinical as she broke four times in her match from just five break points.
Bouchard, 19, broke three times in the first set, dropping her serve once, and broke twice in the second.
Stosur told the WTA website: "I came here the first year of the tournament in 2009 and won the title, and I had a really good time, so I think it's nice to go back to a city and a tournament where you have a good feeling.
"I'm very motivated. I'm really looking forward to tomorrow now. It's going to be great to be in the final again. Hopefully I can repeat what I did four years ago instead of two years ago (when she lost in straight sets to Marion Bartoli in the final)."