- Jesse Spencer as Lieutenant/Captain Matthew Casey
- Taylor Kinney as Lieutenant Kelly Severide
- Kara Killmer as Paramedic Sylvie Brett
- David Eigenberg as Firefighter Christopher Herrmann
- Yuri Sardarov as Firefighter Brian "Otis" Zvonecek (Episode 1)
- Joe Minoso as Firefightern Joe Cruz
- Christian Stolte as Firefighter Randy "Mouch" McHolland
- Miranda Rae Mayo as Firefighter Stella Kidd
- Eamonn Walker as Battalion Chief Wallace Boden
- Annie Ilonzeh as Paramedic Emily Foster
|[[Sacred Ground]]||Writer: Derek Haas||Director: Reza Tabrizi||September 25, 2019||#8x01|
|In the season 8 premiere, the mattress factory fire spirals out of control. Truck and squad lay it on the line in hopes of getting the trapped victims out alive.
|[[A Real Shot in the Arm]]||Writer: Andrea Newman & Michael Gilvary||Director: Sanford Bookstaver||October 02, 2019||#8x02|
|Lt. Casey struggles to get Chief Boden to sign off on an energetic new recruit. Against her better judgment, Foster extends an olive branch to her irritating new medic. Otis inspires Herrmann to seek new partners at Molly's. Brett realizes life in Fowlerton will take some getting used to.
|[[Badlands]]||Writer: Michael A. O'Shea||Director: Olivia Newman||October 09, 2019||#8x03|
|Brett and Foster question the suspicious circumstances surrounding a brutal attack at a juvenile detention center, which leaves them searching for the truth. A convoluted new technology installed inside Firehouse 51 tests everybody's patience. Kidd gets chosen to represent the district at a leadership conference.
|[[Infection: Part 1]]||Writer: Teleplay by : Derek Haas
Story by : Dick Wolf & Derek Haas
|Director: Reza Tabrizi||October 16, 2019||#8x04|
|In the first part of a three-show crossover event, a rare but deadly bacteria takes its toll on numerous victims around the city, leaving Chicago’s finest first responders to work together alongside the CDC to resolve the dangerous situation. Following a fire at a local university that ties into the outbreak, Severide has suspicions that something bigger is happening.
|[[Buckle Up]]||Writer: Matt Whitney||Director: Leslie Libman||October 23, 2019||#8x05|
|Kidd must prove herself at the National Firefighter Leadership Conference while the rest of Firehouse 51 is called to two eerily similar car wrecks. Mouch tries to keep everyone in the firehouse informed by starting a newsletter, but things quickly get out of hand. Cruz deals with a heartbreak.
|[[What Went Wrong]]||Writer: Jamila Daniel||Director: Sanford Bookstaver||October 30, 2019||#8x06|
|Cruz and Severide suspect foul play when a fire started by an elderly woman turns deadly. Kidd, Foster and Brett create a women’s-only lounge. Firehouse 51 celebrates some good news.
|[[Welcome to Crazytown]]||Writer: Andrea Newman & Michael Gilvary||Director: Carl Seaton||November 06, 2019||#8x07|
|Severide must make a tough decision about the future of his career at Firehouse 51. Herrmann deals with the consequences of his temper after a run-in with a Chicago police officer. Cruz is excited to demonstrate the Slamigan at the Firefighting Expo. Commissioner Grissom returns.
|[[Seeing is Believing]]||Writer: Ron McCants||Director: Eric Laneuville||November 13, 2019||#8x08|
|Severide begins his assignment at the Office of Fire Investigation and gets off on the wrong foot when, despite his orders, he reopens an old case. When the cause of an apartment fire hits close to home, Herrmann is on a mission to get to the bottom of it. Kidd finds herself burning the candle at both ends.
|[[Best Friend Magic]]||Writer: Derek Haas||Director: Reza Tabrizi||November 20, 2019||#8x09|
|An unexpected visit throws Casey for a loop. Severide sets out to exonerate a wrongly convicted arsonist. Kidd pays the price for burning the candle at both ends. Cruz goes on a mission to fix one of Otis’s old toys.
|[[Hold Our Ground]]||Writer: Michael A. O'Shea||Director: Matt Earl Beesley||January 8, 2020||#8x10|
|Members of Firehouse 51 are dismayed to learn their boundaries have been redrawn to overlap with an adjacent station and problems quickly arise. Casey and Gallo hunt a missing piece of equipment. Brett and Foster find themselves at odds. Mouch tries the find the recipient of a mysterious letter he discovers.
|[[Where We End Up]]||Writer: Batan Silva||Director: Batan Silva||January 15, 2020||#8x11|
|A pest control problem forces the 51 team to temporarily bunk with Firehouse 20. All under the same roof, Casey clashes with Capt. Delaney while Foster, Kidd and Brett fear Capt. Leone has it out for them. Boden mulls a procedural overhaul.
|Then Nick Porter Happened||Writer: Andrea Newman and Michael Gilvary||Director: Reza Tabrizi||January 22, 2020||#8x12|
|A series of false alarms at a private school hinders the firehouse's ability to respond to legitimate emergency calls. Kidd asks for ideas to surprise Severide on his birthday. Cruz and Brett rent out their extra room, but the new tenant is more than they bargained for.
|A Chicago Welcome||Writer: Derek Haas||Director: Paul McCrane||February 05, 2020||#8x13|
|The surprising arrival of a new fire truck brings both joy and chaos to members of Firehouse 51. Boden and Severide are asked to make peace with an old foe for the greater good. Brett receives family news while Foster plans a party with friends.
|Shut It Down||Writer: Neil McCormack||Director: Leslie Libman||February 12, 2020||#8x14|
|A series of mysterious gas leaks has members of Firehouse 51 puzzled and spread thin. Brett's conflicted when her birth mother gets serious about tracking her down. Severide misunderstands his role as Cruz's best man. Mouch bites off more than he can chew.
|Off The Grid||Writer: Matt Whitney||Director: Reza Tabrizi||February 26, 2020||#8x15|
|In a two-show crossover event with "Chicago P.D.," a series of teen opioid overdoses sees Severide partner with Sean Roman, but begins to suspect there's more to the story than his old friend is telling him. Casey tries to be there for Brett as she considers her birth mother's offer to meet.
|The Tendency of a Drowning Victim||Writer: Andrea Newman and Michael Gilvary||Director: Matt Earl Beesley||March 04, 2020||#8x16|
|Boden is on edge after starting a new fad diet. Casey and Severide disagree on a call. Brett's birth mother shares life-altering news. A familiar face has a proposition for Herrmann.
|Protect a Child||Writer: Derek Haas||Director: Brenna Malloy||March 18, 2020||#8x17|
|Things get personal for Casey and Gallo in the aftermath of a suburban house fire involving a mother and her young son. Herrmann campaigns for more respect. Kidd has an idea for giving back to her community.
|I'll Cover You||Writer: Teleplay by : Michael Gilvary & Andrea Newman
Story by : Ron McCants & Michael A. O'Shea
|Director: Eric Laneuville||March 25, 2020||#8x18|
|Lt. Severide teams up with Seager and the OFI when a motel structure fire turns suspicious. Firehouse 51 members become amateur sleuths following a Reddit post involving one of their own. Brett continues to get invested in her birth mother, Julie.
|Light Things Up||Writer: Elizabeth Sherman||Director: Nicole Rubio||April 08, 2020||#8x19|
|Tension builds when a group of rabble-rousers attempt to lock down the firehouse. Brett is faced with a monumental decision. Cruz readies himself for a big day. Gallo and Ritter attempt to launch Firehouse 51 into the social media age.
|51's Original Bell||Writer: Matt Whitney||Director: Eric Laneuville||April 15, 2020||#8x20|
|When one of 51's own gets injured on a call, Lt. Severide becomes obsessed with helping out. Foster contemplates a big decision. Kidd is concerned for one of her high school trainees.
Notes and Trivia
- On March 13, 2020, the production of the eighth season was suspended due to the coronavirus outbreak. Only 20 episode out of the planned 23 were completed.