Sabalenka's power was too much for the defending champion, who was looking to become the first female player in the Open era since 1968 to win four consecutive titles in Paris.
Swiatek had won the previous three editions along with her maiden crown in 2020
The top seed will play either France's wild card Lois Boisson or second seed Coco Gauff in Saturday's showcase match.
"Honestly, it feels incredible but I understand the job is not done yet. I'm just thrilled today with this win and the atmosphere," Sabalenka said.
"She's the toughest opponent, especially on clay, especially at Roland Garros. It was a tough match it was a tricky match but I managed."
Sabalenka, playing her second French Open semi-final and seeking her first title in Paris, powered into a 3-0 lead, twice breaking the Pole. She kept attacking her opponent's serve, with Swiatek winning just 35% of her points on her second serve.
Swiatek, who late last year accepted a one-month doping ban and came into the tournament without a single title win this season, had reached the semi-final,s dropping just one set in five matches. But she looked completely out of sorts.
With seven unforced errors in the first three games, she was playing catch-up from the start.
The Pole, struggled with her serve and had racked up two double faults by the fifth game.
She gradually, however, found her range and precision, countering Sabalenka's raw power with superb ball placement and levelled when her opponent double-faulted on break point.
The Belarusian was furious, angrily shouting to her team in the box, before overrunning her opponent in the tiebreak.
The pair traded breaks at the start of the second set before Swiatek earned another to level the match.
Sabalenka bagel
But Sabalenka was not to be denied, breaking the 24-year-old world number five at the start of the third to take control.
"I think the pace from her was super fast," Swiatek said. "Especially at the beginning of the match, she played just kind of as hard as possible and pretty risky. So it was just hard to get into any rally."
"In the third set I feel like we kind of came back to what happened in the first, and she for sure used her chances, and I didn't really keep up what I was doing in the second set."
Sabalenka gave her opponent no chance with her thunderous groundstrokes, powering through the decider as Swiatek ran out of steam.
"It could not be more perfect than that," Sabalenka said of her third-set performance.
"I'm super proud right now, I'm glad I found my serve (again in the third set)."