The first candidate to enter the race was New York City Council Member Helen Rosenthal, who filed to run for the position on June 16, 2018, three years before the election was due to take place.

[7] Benjamin's base of support was primarily concentrated in Upper Manhattan, and he posted strong fundraising numbers following his announcement.

[7] By this stage of the campaign Lander was considered the frontrunner by the Gotham Gazette, as his base of support among left-wing Democrats was not limited to a single borough.

[8] Parker was noted by the Gazette as having posted weak fundraising numbers in comparison to the other candidates, and he had a history of personal controversies that were considered potential hindrances to his campaign.

[11] In February 2021, Speaker of the New York City Council Corey Johnson, who had waged an abortive campaign for mayor the previous year, began to privately signal that he was interested in running for Comptroller.

[13] However, Johnson had also undergone a politically damaging fight the previous year over the budget of the New York Police Department, where his attempts to bridge the gap between factions who wanted to maintain the department's budget and those who wanted to reduce it considerably had left him unpopular with both.

[18][5] The following candidates (listed alphabetically) held office, were included in polls, or were the subject of significant media coverage.