Shadowhunters was based on the book The City of Bones in the Mortal Instruments series. They first made the movie The Mortal Instruments that started production in September 2014 but then was delayed till 2014 but was then eventually cancelled. Then on October 2014, it was announced that The Mortal Instruments would air on tv as tv series. The producer says that the movie that was previously made, left so much information out on the series. To them, it made more sense to making into a tv series.
The series was produced by Constantin Film and airs on freeform. The first episode aired on January 12, 2016. The first season had 13 episodes and finished the season on April 5, 2016. The show was renewed in March 2016 for a new season that will consist of 20 episodes. The first episode of the second season aired at January 2, 2017. The series began filming on May 25, 2015 in Toronto, Canada.