Defiance was developed as a transmedia project from the start, with the TV series connected to a video game produced by Trion Worlds, announced together by Syfy in June 2011.

Production of the game led to a later expansion; in 2016 Trion Worlds updated the game as a promoted 'season four' of the show, though they stated they had no plans to make an actual sequel series.

Grant Bowler, who plays lawkeeper Joshua Nolan, was the first actor cast in the series, announced in January 2012.

Gillian Anderson was briefly considered by the producers to play either Amanda or Stahma, but the idea was dropped as they assumed she would not be interested in returning to episodic television.

Production of the first season began in April 2012 in Toronto.

Language creator David J. Peterson developed full constructed languages for the Castithan and Irathient races, and by the end of the series had created four full languages with their own scripts, including Indojisnen and Kinuk'aaz.

Composer Bear McCreary scored both the TV series and the video game, crafting distinct musical identities for each alien race, including street music, ceremonial pieces, alien classical music, jazz, rock anthems and torch songs.

The show's second season achieved a 100% approval rating on Rotten Tomatoes based on 8 reviews, a notable jump from the first season's 61% rating.