2021 Miami Open – Women's singles

Women's singles
2021 Miami Open
Champion Ashleigh Barty
Runner-up Bianca Andreescu
Score6–3, 4–0, ret.
Draw96
Seeds32

Defending champion Ashleigh Barty won the women's singles tennis title at the 2021 Miami Open after Bianca Andreescu retired from the final with the scoreline at 6–3, 4–0. Barty saved a match point en route to the title, in the second round against Kristína Kučová.

Barty and Naomi Osaka were in contention for the WTA No. 1 singles ranking. Barty retained the top ranking by winning the title after Osaka lost to Maria Sakkari in the quarterfinals, ending a 23-match winning streak dating to the 2020 Cincinnati Masters.