Stephens had dominated the first set, scoring two early breaks to race into a 4-0 lead against a hesitant Svitolina. She's playing good tennis. Obviously, to make a final of another tournament is incredible. It's three finals on the year for me. I'm really pleased with that.
Barty had to bounce back quickly from a tough loss against World No.1 Simona Halep in singles earlier in the day, partnering with Schuurs for their semifinal.
Barty will play the Romanian for the first time after dispatching Kiki Bertens 6-3 6-1 in less than an hour to extend her flawless record over the Dutchwoman to two matches.
The world No 1 was in control from the outset against a nervous-looking Australia's Ashleigh Barty, whose challenge was undone by a string of unforced errors.
"I was pretty close [to winning] the last time so I'm just going to go out there and play hard", Stephens, who trails Halep 6-2 in head-to-head contests, said.
After a pep talk from coach Andrew Bettles, Svitolina attempted to match the power game of her opponent, holding twice and then breaking Stephens to get back to 3-5. I was upset. I am upset.
Stephens, preparing for her US Open title defence, broke the Ukrainian's serve five times to reach the final without having dropped a set through the tournament.
The 15th-seeded Barty won 80% of her first serve points and broke Bertens four times as she cruised to victory.
The Romanian showed her class as she broke Barty's serve in the opening game with an impressive series of forehands down the lines.
"I can play my singles, do my best in my singles, then worry about the doubles when we have to". "I pushed her very back on her backhand, then I could just receive a shorter ball, an easier ball for me to open the court".
"Then I just went all the way on her forehand - short, cross, long, everything. I played some slices".