Barty, runner-up at Wuhan last year, staved off an early fightback from world number three Kerber to seal her first win over a top-10 player this year in an hour and 17 minutes.
"She's always difficult to play against. She's one of the best players in the world, and you have to come out here, enjoy and have fun, and try and play as well as you can," Australian Barty said.
Australian Open winner Caroline Wozniacki fell to qualifier Monica Puig, losing 7-6(10) 7-5 for her second defeat by the Puerto Rican this season following a loss in Miami.
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The Dane has not won a trophy since lifting the Eastbourne title in June.
Up next for Puig is local hope Wang Qiang who is looking to secure back-to-back titles after winning in Guangzhou last week. Wang powered past Daria Gavrilova 7-5 6-2.
Spain's Garbine Muguruza's patchy form this season continued as she was beaten 7-6(3) 7-6(1) by Czech qualifier Katerina Siniakova in a tightly-contested clash.
It was Siniakova's second upset in as many rounds after she knocked out defending champion Caroline Garcia on Tuesday and the world number 47 faces Anett Kontaveit next. The Estonian advanced with a 6-4 4-6 6-1 win over Zhang Shuai.
Twice champion Petra Kvitova surrendered a one-set lead before losing 3-6 6-3 6-3 to unseeded Anastasia Pavlyuchenkova, a result that ensured a new winner will be crowned in Wuhan.
"It's my first top five win in a while, so that means a lot and it's special. Petra's a super tough opponent, and I knew that," said Pavlyuchenkova, who faces Barty next. (Reporting by Shrivathsa Sridhar in Bengaluru Editing by Toby Davis)
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