The ninth season of Chicago Fire, an American drama television series with executive producer Dick Wolf, and producers Derek Haas and Matt Olmstead, was ordered on February 27, 2020, by NBC.

[2] On April 16, 2020, it was announced that Annie Ilonzeh, who portrayed Paramedic Emily Foster, would depart the series after two seasons.

[20] On September 14, 2020, it was announced that Adriyan Rae was joining the cast as series regular Paramedic Gianna Mackey.

[24] Former series regular Monica Raymund was set to return towards the end of the season but was unable to due to COVID restrictions.

[2] On November 11, 2020, it was reported that the ninth season had suspended production for two weeks due to multiple positive COVID-19 tests.