Fresh from winning the Korea Open on Sunday, which shot her world ranking to No.41, Birrell took just 59 minutes to trounce Japan's 361st-ranked Aoi Ito 6-1 6-1 in Beijing on Thursday.
And Hunter needed seven minutes more to cruise past China's Lin Yujun 6-2 6-1.
Both Australians will face far sterner tests in the second round at the 128-player hardcourt event.
Birrell takes on 18th seed Marie Bouzkova of Czechia, while Hunter plays Greek 25th seed Maria Sakkari. Both rivals had first-round byes.
The news was bad, however, for Australia's Daria Kasatkina, with the world No.87 falling in a tight three-setter against Spain's Paula Badosa, 4-6 7-6 (9-7) 6-4.
Badosa converted eight of 10 break points while Kasatkina could only capitalise on eight out of 19.
In a match commensurate with what is now the pair's 4-4 head-to-head record, Kasatkina took the first set in converting three of nine break points to Badosa's two of three.
Badosa only required the same strike rate in a gripping second set, while successfully defending three of the five break points against her own serve, then converted all four break opportunities in claiming the third set.
The Spaniard will next play 24th seeded Latvian Jelena Ostapenko.
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