The series is based on the best-selling novels The Marmalade Files, The Mandarin Code, and The Shadow Game, written by journalists Chris Uhlmann and Steve Lewis.

Authors Chris Uhlmann and Steve Lewis joined the sequel series as story consultants, even though its storyline departs from their original books.

The series premiered on Foxtel's Showcase in Australia on 5 June 2016 before later reaching Netflix internationally on 26 June 2018.

A sequel, Secret City: Under the Eagle, was green-lit in February 2018 and launched worldwide on Netflix on 6 March 2019, just two days after its Australian premiere.

Secret City: Under the Eagle was later removed from Netflix in March 2026.

American actor Mekhi Phifer was cast as Brent Moreton, the US Ambassador to Australia, in the first season.

The character Kim Gordon, a senior analyst in the Australian Signals Directorate played by Damon Herriman, was originally married to protagonist Harriet Dunkley but was divorced by her after transitioning into a woman.