Sabalenka saved seven break points at 5-5 and then forced the stubborn Briton, ranked 56th in the world, into a rare backhand error to clinch the opening set.
The Belarusian notched another must-win break in the second set to again draw level at 5-5 before triumphing in a tie-break by slamming down an unreturned serve.
She will battle Italy's Jasmine Paolini in the next round for a place in the quarter-finals.
World number four Jessica Pegula bounced back from a set down on Tuesday to beat Russia's Anna Blinkova 6-7 (2/7), 6-2, 6-1.
France's world number 10 Caroline Garcia suffered a second-set wobble before downing Kazakhstan's Yulia Putintseva 6-3, 3-6, 6-3.
The women's draw continues through Tuesday with US teenage starlet Coco Gauff taking on Petra Martic of Croatia for a place in round three.
World number two Iga Swiatek is also in action against France's Varvara Gracheva.
The China Open is taking place for the first time since 2019 after Beijing ditched its isolationist zero-Covid policy.
