Following up on her win at the Pan Pacific Open, Australian Open champion Osaka reached another final by impressively defeating Wozniacki, a two-time winner of this tournament, 6-4 6-2.
She will now do battle with Barty — who regained the world No.1 ranking from Osaka after the US Open — in Beijing on Sunday, bidding for a second career premier mandatory title.
Barty had earlier saved a match point to earn a thrilling 6-3 3-6 7-6 (9-7) victory over Kiki Bertens in a battle lasting two hours and 20 minutes, the Australian reaching her fifth final of 2019.
Osaka fired 30 winners to Wozniacki's 13 and converted three of her five break points as her assertive style proved decisive in a 65-minute victory.
Wozniacki had incredibly won 20 consecutive sets at the China Open dating back to her 2018 victory at the event, but failed to take any of her seven break points as that spectacular run came to an emphatic end.
Osaka saved one of those break opportunities to level a close first set at 4-4 before building on that momentum.
She made the decisive break with a forehand winner down the line in the next game and then held to claim the first set, sealing the opener with a powerful volley.
The second set was more comfortable, as Osaka's momentum continued with a break in the opening game.
Wozniacki had chances, though, with two missed opportunities to break straight back and another going begging that could have prevented her Japanese opponent moving into a 3-1 lead.
Osaka then broke again to move into complete control and an unreturned serve on her first match point soon after finished the job.
Barty had needed three sets to move through her previous two matches and was pushed to the limit again in her semi-final.
Asked about winning the crucial points, Barty said: "That's gone hand-in-hand with adding some new people to my team, trying to work with them behind the scenes.
"Not just for my tennis, it's for my life, my health and wellbeing as well, which has been the best thing. I have never been happier off the court, never been happier on the court. It's been a brilliant time in my life.
"I enjoy those moments. I enjoy when it's tight, when your back's against the wall. That really brings out the fun for me."
The world No.1, who had won all four of the previous meetings between the pair, claimed 12 of the first 14 points, breaking in the second game.
That strike was all she needed in order to claim the opening set, as Bertens threatened to recover at 5-3 down only for Barty to eventually convert her sixth set point.
It was Bertens's turn to make a fast start in the second set, though, racing into a 3-0 lead and not conceding a break point en route to levelling the match.
That led to a dramatic final set where both players broke twice, Bertens failing to serve out the match at 5-4 as Barty forced an epic tie-break.
Barty lost the first three points but recovered to lead 6-5 before being unable to convert a match point on her own serve. Her Dutch rival then missed her chance at victory having moved 7-6 ahead.
The Australian won three straight points from there, sealing victory with her second match point after Bertens sent a backhand return long.