Williams, who had been sidelined by a left ankle injury, fired six aces and connected on 64 percent of her first serves while surrendering only one service break to advance into the third round with an 80-minute triumph.
The 13-time Grand Slam singles champion will next face Italy's Roberta Vinci, who ousted Bulgarian Tsvetana Pironkova 7-5, 6-1.
Former World No. 1 Williams played for the US Fed Cup team last month, winning two singles matches in a 5-0 World Group II victory over Belarus.
But she had not been in a tour match since losing to Russia's Ekaterina Makarova in the round of 16 at Melbourne.
Five-time Miami winner Williams, the 10th seed on the women's side of the $9.6 million event, withdrew before her Brisbane quarter-final match because of the ankle injury in her only other WTA start this year.
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