The 19-year-old Pole, ranked world No. 16 by the Women's Tennis Association (WTA), saw off Czech player Barbora Krejčíková 6-4, 6-2 in their second-round encounter on Thursday.
Up next for the rising Polish tennis star at the tournament in the United States is Ana Konjuh of Croatia.
The 2021 Miami Open began on March 22 and runs until April 4.
Świątek last month won the Adelaide International tournament in Australia, claiming her second singles title.
Earlier in February, she reached the fourth round of the women’s singles at the 2021 Australian Open, where she lost to Romania's Simona Halep.
The Polish teenager in October won the French Open, claiming her maiden Grand Slam title and becoming the first Pole to lift a Grand Slam singles trophy.
(gs/pk)
Source: IAR, PAP