The 2021 Miami Open was a professional hardcourt tennis tournament played from March 23 to April 4, 2021, on the grounds of Hard Rock Stadium in Miami Gardens, Florida in the United States.

The 2020 edition was postponed due to the onset of the COVID-19 pandemic in Florida.

[2] Roger Federer and Ashleigh Barty were the defending champions from 2019 in the men's and women's singles respectively.

Barty successfully defended her title, defeating Bianca Andreescu in the final, 6–3, 4–0, retired.

^ Points form 2019 Miami, 2019 Guadalajara, 2019 Charleston and 2019 Monterrey will be dropped on Monday, April 5; 2019 Indian Wells will not be mandatory anymore ¡ Miami will not be considered a mandatory result that must be counted as part of a player's best 16 results[6] † The player did not qualify for the tournament in 2019.