In a gruelling 2hr 41min battle, French Open champion Halep prevailed 7-6 (8/6), 3-6, 6-4 over Stephens in a repeat of the duo's meeting in the final of Roland Garros earlier this year.
American third seed Stephens surged into Sunday's final against world number one Halep after overpowering Svitolina 6-3, 6-3 in the day's second semi-final.
Sloane Stephens, ranked a career-high third, suffered a first-round Wimbledon exit after falling to Simona Halep in last month's French Open.
Simona Halep is still waiting for a maiden Grand Slam title after three previous final defeats, while Sloane Stephens is the reigning US Open champion.
Simona Halep will have an opportunity to finally lift a Grand Slam trophy when she faces US Open champion Sloane Stephens in her third French Open final on Saturday.
Simona Halep reached her third French Open final where she will face US Open winner Sloane Stephens for the title.
French Open: Sloane Stephens produced a clinical performance to down Daria Kasatkina, the conqueror of world number two Caroline Wozniacki.
Simona Halep of Romania continued to lead the Women's Tennis Association rankings.
Sloane Stephens beat Jelena Ostapenko 7-6 (7/5), 6-1 to lift the Miami Open title for the first time.
Sloane Stephens will enter the top 10 for the first time next week when the WTA rankings are announced.
The United States duo of Shelby Rogers and CoCo Vandeweghe beat Belarusian duo Aryna Sabalenka and Aliaksandra Sasnovich to clinch Fed Cup crown for the 18th time.
CoCo Vandeweghe, this season's Australian Open and US Open semi-finalist, ranked 10th in the world, fired 12 aces to win the match against Aryna Sabalenka of Belarus.
CoCo Vandeweghe won her Fed Cup match 6-4, 6-4, in one hour 27 minutes her first ever meeting with the 23-year-old Aliaksandra Sasnovich.
The United States Fed Cup team is made up of world number 10 CoCo Vandeweghe, US Open champion Sloane Stephens, Shelby Rogers and Alison Riske.
Garbine Muguruza officially became world number one for the first time on Monday.
Stephens, who won only $310,000 this year after being sidelined for 11 months until July by a left foot injury, said her desire for more major titles was definitely fueled.
Former world number 1 and 23-time Grand Slam champion Serena Williams made her first public comments since giving birth to a daughter one week ago