American Gauff scored a 4-6 6-4 6-2 win in Beijing on Saturday and will next face the winner of the second semi-final between Paris Olympics gold medallist Zheng Qinwen and Karolina Muchova in Sunday's final.
"It was just a tough match. I just tried to stay focused. Mentally I tried to reset. I got down a couple of times, but I tried to bounce back," Gauff said in her post-match interview.
Coco Gauff and Paula Badosa embrace after their three-set battle at the China Open. (AP PHOTO)
Double faults and a weaker second serve troubled world No.6 Gauff early in the match as Badosa won 75 per cent of her second return points in the set.
Badosa broke to go up 3-2, but Gauff fought back to 4-4 after a marathon game in which Badosa saved 10 break points but a persistent Gauff ultimately prevailed.
The world No.19 reclaimed the lead with a quick break in the  next game and held her own serve to win the set.
Badosa broke again in the first game of the second set and almost built a 4-1 lead, but fourth-seeded Gauff saved four break points to hold.
The American would not lose another game in the set as she seized the momentum, landing more precise shots across the court, with Badosa not winning a single point as Gauff broke her in the last game.
In the third set, the 20-year-old American broke twice to build a 4-1 lead, hitting two aces as her powerful forehands eluded an increasingly exhausted Badosa.
Gauff sealed victory with another break.
"I had tough opponents the whole tournament. Happy to be in the final," Gauff said.
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