The Belarusian pummelled Kenin with a succession of mighty serves and groundstrokes and wrapped up the opening set with an ace after just 23 minutes.
She broke serve twice more in the second set as Kenin - playing with heavy strapping on her left thigh - failed to muster a response.
Sabalenka sealed the match with yet another unreturned serve to set up a tie against either Magdalena Frech (25) or Katie Boulter (27) in the next round.
All of the world's top eight are taking part in the women's draw this year, with second-ranked Iga Swiatek (22) due to play Spain's Sara Sorribes Tormo.
The China Open is taking place for the first time since 2019 after Beijing ended its isolationist zero-Covid policies.
The women's tournament is also in action for the first time since the global governing body ended a boycott of China this year.
The embargo had been declared after Chinese player Peng Shuai (37) made sexual assault accusations against a top government official.
