Most of the opening games went with serve until Rybakina broke the Belarusian late on and forced her into a wild forehand to take the set.
Sabalenka gave up another two service games in set two - the latter when she double-faulted twice from deuce - to put Rybakina into a commanding lead.
And the six-foot Kazakh made no mistake, seeing out an ace-laden performance with a 40-0 game topped off with a crushing cross-court forehand winner.
Rybakina will play Russia's Liudmila Samsonova in the final four after the world number 22 beat Jelena Ostapenko of Latvia 6-3, 6-2.
Swiatek to play Gauff
Iga Swiatek will play US Open champion Coco Gauff in the other semi-final after the world's second and third-ranked players both won earlier Friday.
World number two Swiatek came from a set behind to defeat Caroline Garcia 6-7(8), 7-6(5), 6-1 in a match that hinged on two nail-biting tie-breaks.
Swiatek endured a tense opening set that the Frenchwoman - ranked 10th - eventually stole with a vicious passing shot at the end of a marathon tie-break.
The Pole was 4-1 up in set two but threatened a match-ending collapse against a stubborn Garcia, finally edging it when she netted a limp backhand.
From there, Swiatek took control, notching a double break in the deciding set and finally taking match point at the fifth time of asking.
"For sure, it was really intense. We played really fast," the four-time Grand Slam winner told a post-match news conference.
"There was no time sometimes to think or analyse. I'm happy I used my intuition a lot," she said.
"I just knew that she was risking, so... her mistakes could come."
'Comfortable as it looked'
Gauff hailed a "comfortable" victory after she disposed of world number six Maria Sakkari 6-2, 6-4.
The 19-year-old sailed through a rapid first set and made short work of her opponent in a dominant second, breaking serve in the fifth game.
She took the match by thundering down a meaty serve that Sakkari could only return wide.
"It was definitely as comfortable as... it looked, honestly," Gauff said after the match.
"Some days you just feel like no matter what's going to happen, you're going to win," she said.
"When I woke up today, I just felt good. It's a rare feeling as an athlete."
The China Open is taking place for the first time since 2019 after Beijing ended strict zero-Covid travel curbs.
The men's competition concluded on Wednesday, when Italy's Jannik Sinner beat world number three Daniil Medvedev in the final.
