Development Amazon Studios chief Jennifer Salke first came up with the idea for the series and approached the
Russo brothers and their independent studio
AGBO about creating an ambitious, global spy show in mid-2018. The series was originally a partnership between AGBO and the screenwriting collective Midnight Radio, comprising
Josh Appelbaum and
André Nemec. Appelbaum and Nemec departed the show during production in 2021, due to creative differences with the Russos. The Russos set up a second editing team and cut an alternate version of the season to compete with the main team, and Amazon chose the Russos' version after focus-group testings. This led to the hiring of
David Weil as the new showrunner and extensive reshoots in 2022. As of 2023,
Citadel was the second most expensive series of all time with a budget of US$300 million, largely due to the reshoots following Weil's hiring. Prime Video renewed the series for a second season on March 14, 2023.
Casting Starring alongside Madden and Chopra,
Roland Møller will play Laszlo Milla, a lead operative of Citadel's rival intelligence agency, Manticore.
Filming Filming on the main series began in January 2021 and
wrapped the following December. However, reshoots occurred in early and mid-2022 under the supervision of Weil,
the Russos, and director
Thomas Sigel. ==Episodes==