The world number two, chasing a 23rd Grand Slam singles title, won 6-1 6-3 in 63 minutes on Rod Laver Arena.
Williams, 35, goes on to face Czech 16th seed Barbora Strycova, who beat France's Caroline Garcia 6-2 7-5.
"She's human, and she is beatable," Strycova said of facing Williams in the last 16.
"This is a Grand Slam, and we are talking that she already won, but I don't like these talks."
Russian 30th seed Ekaterina Makarova came through a dramatic match to beat Slovakian sixth seed Dominika Cibulkova 6-2 6-7 (3-7) 6-3.
Croatian veteran Mirjana Lucic-Baroni also advanced to the fourth round for the first time with a 3-6 6-2 6-3 win over Greece's Maria Sakkari.
Before this year, the 34-year-old Lucic-Baroni's only previous win at the Australian Open came back in 1998.
She next faces American qualifier Jennifer Brady, the world number 116 who followed up her second-round win over Heather Watson by defeating 14th seed Elena Vesnina 7-6 (7-4) 6-2.
Six-time champion Serena Williams eased past fellow American Nicole Gibbs to reach the fourth round of the Australian Open in Melbourne.