American Jessica Pegula beat Spain's Paula Badosa 6-2 3-6 6-3 in a much tougher second semi-final that was briefly suspended due to rain.
Belarusian world number three Sabalenka showcased her prowess with a fast-paced, aggressive style in her third meeting of the season with Swiatek, and the first on a hard court.
"I wasn't over-rushing things. I was trusting myself a lot, and I wasn't trying to over-hit the ball," Sabalenka said.
"I was just trying to stay there, put as much pressure as I can on her, and I was really focused on my serve."
Despite a valiant effort to mount a late comeback, Swiatek struggled to keep up with Sabalenka's pace and precision and was ultimately unable to close the deficit.
For Pegula, who won the Canada Open last week, it was her ninth consecutive victory. She will now aim to become the first woman since Evonne Goolagong in 1973 to win the Canada and Cincinnati titles in the same year.
Sabalenka will compete in her ninth WTA 1000 final on Monday, while it will be the fifth for Pegula.
