Hubert Hurkacz defeated Jannik Sinner in the final, 7–6(7–4), 6–4 to win the men's singles tennis title at the 2021 Miami Open.

[1] Roger Federer was the reigning champion from when the tournament was last held in 2019, but chose not to participate this year.

[2] As both Novak Djokovic and Rafael Nadal also chose not to participate, this was the first Masters 1000 tournament since the 2004 Paris Masters without at least one member of the Big Three competing.

[3] All seeds received a bye into the second round.

Click on the seed number of a player to go to their draw section.