The Belarusian snapped Swiatek’s French Open winning streak at 26 matches with a 7-6 (7/1), 4-6, 6-0 success to reach her first final in the clay-court Grand Slam.
“Iga is the toughest opponent, especially on the clay and at Roland Garros,” said Sabalenka after becoming the first player to defeat Swiatek in a deciding set at the French Open.
“I’m proud that I was able to get this win.”
World number two Gauff ended the dream run of 361st-ranked wildcard Boisson with a 6-1, 6-2 victory in the second semi-final on Court Philippe Chatrier.
Gauff and Sabalenka are level at 5-5 in their head-to-head record and have won one each of their two meetings at major tournaments.
Sabalenka edged a topsy-turvy first set that featured eight breaks of serve in a tie-break, before Swiatek hit back to level the match.
The finale turned out to be a complete anti-climax, as Swiatek made 12 unforced errors in the third set and won only six points.
“I’m glad that I found my serve. It was a bit easier with the serve,” added the 27-year-old Sabalenka. “What can I say, 6-0 – it couldn’t be much more perfect than that.”
Sabalenka is targeting a fourth Grand Slam title and first not on hard courts, after winning last year’s US Open and the Australian Open back-to-back in 2023 and 2024.
Swiatek has still not reached a WTA final since lifting the Coupe Suzanne Lenglen 12 months ago.
She showed signs of a revival on the Paris clay where she has dominated since winning as a teenager in 2020, but her game deserted her in the deciding set as she slipped to only the third French Open defeat of her career.
“I love playing here, so for sure I’m happy that I was fortunate enough to play so many great tournaments here,” Swiatek said.
Sabalenka has now won their last two meetings, and five of 13 in total.
This was the first time the pair, the dominant players in women’s tennis of the past few years, have gone head-to-head at a Grand Slam tournament since Swiatek’s win in the 2022 US Open semi-finals en route to the title.
Sabalenka will be the favourite to lift the trophy when she takes on Gauff, to whom she lost in the 2023 US Open final.
Swiatek, who was bidding to become the first woman to win four successive French Opens in over a century, will drop to seventh in the world rankings next week.
Boisson had got the better of third seed Jessica Pegula and world number six Mirra Andreeva in the previous two rounds but the test provided by Gauff proved to be a step too far.
The home crowd were silenced by a ruthless opening set from the second seed.
Boisson briefly raised the French fans from their slumber by breaking back in the second set, only to immediately surrender it straight back.
Gauff clinically finished the job after just 69 minutes on court to book her spot in a second French Open final.
“When you guys were chanting her name, I was thinking my name,” Gauff told the crowd in her on-court interview. “Obviously there’s still a lot of work to do, but for now I’ll enjoy this one and then prepare for the final tomorrow.”
The 21-year-old suffered an emotional defeat by Swiatek in the 2022 final, but will believe she can finally win the tournament in which she has made at least the quarter-finals in five straight editions.
Boisson had been hoping to become only the second Frenchwoman to win the title in the Open era after Mary Pierce, but went out in a blaze of 33 unforced errors.
“Of course I’m really disappointed today, because obviously I wanted to go further than this semi-final, but I’m just going to take the time to digest this,” said the 22-year-old.
She will climb into the world’s top 70 next week and has added US$789,536 to her previous career prize money of US$148,009. (AFP)