With the three other seeds in the last eight of the WTA Premier hard-court event all progressing, the Ukrainian's victory over seventh seed Kerber represented the only surprise of the day in China.
The unseeded Svitolina, bidding to reach her third Tour final, wasted one opportunity to take the first set when she allowed Kerber to break back when serving at 5-4 up.
She recovered her composure, though, and hit back immediately to move in front with a second successive break.
It looked as though the match would go to a decider when Kerber stormed into a 4-1 lead in the second, but Svitolina roared back to force a tie-break, which she dominated from the early stages to book her place in the last four.
There she will meet 2014 Wimbledon champion Petra Kvitova, who breezed past Caroline Garcia 6-3 6-4.
Caroline Wozniacki had more trouble in seeing off qualifier Timea Bacsinszky, the world number one coming from a set down to eventually prevail 4-6 6-2 6-3.
Bacsinszky, who defeated Maria Sharapova in straight sets in the previous round, got off to an ideal start when she took the opening set courtesy of breaks in games three and seven.
That was as good as it got for the Swiss, however, as world number seven Wozniacki reeled off four consecutive games at the end of the second set, before a crucial break in game eight of the decider saw her progress.
Wozniacki will now take on Eugenie Bouchard after the Wimbledon runner-up came through against the unseeded Alize Cornet 6-3 7-5 in a match that included 10 breaks of serve.