The 2021 ATP Challenger Tour calendar comprised 147 tournaments with prize money ranging from $36,680 up to $156,240.

Tallon Griekspoor set a new record for winning the most Challenger titles in a season when he won his seventh title of the season at the Tenerife Challenger and immediately improved upon the record by winning the Slovak Open II the week after.

[1] This is the complete schedule of events on the 2021 calendar, with player progression documented from the quarterfinals stage.

These tables present the number of singles (S) and doubles (D) titles won by each player and each nation during the season.

The players/nations are sorted by: 1) total number of titles (a doubles title won by two players representing the same nation counts as only one win for the nation); 2) a singles > doubles hierarchy; 3) alphabetical order (by family names for players).