[12] When announcing the series, Dungey said, "No one can interweave the jeopardy firefighters face in the line of duty with the drama in their personal lives quite like Shonda, and Grey's signature Seattle setting is the perfect backdrop for this exciting spinoff.

"[21] Patrick Moran, president at ABC Studios, added that "We talked [with Shonda] about the elements of Grey's Anatomy that seem to resonate with the audience—emotional storytelling, deep human connection, a high-stakes environment and strong and empowered women—and those elements will carry over to the spinoff.

[26] On July 26, 2017, Jaina Lee Ortiz was cast as the female lead, Andrea "Andy" Herrera.

On October 6, 2017, Grey Damon was cast as Lieutenant Jack Gibson, Jay Hayden as Travis Montgomery, Okieriete Onaodowan as Dean Miller, Danielle Savre as Maya Bishop, and Barrett Doss as Victoria "Vic" Hughes.

[28][29][12] They were shortly followed by Miguel Sandoval as Captain Pruitt Herrera,[30] and Alberto Frezza as police officer, Ryan Tanner.