Jang Won-seok began his career as a production assistant for The Adventures of Mrs. Park (1996). He proceeded step by step as a film producer going through a lot of mainstream films, including The King and The Clown. He made a successful debut as an executive producer by developing Secret Reunion(2009), and repeated the feat with War Of The Arrows (2011). In 2011 - 2012, he pumped out many films as an executive producer such as Ghost Sweepers (2012), co-produced Confession Of Murder (2012), and also contributed to the production of critically-acclaimed thriller A Hard Day (2013). In 2013, he co-executive produced Don Lee’s action film The Outlaws (2017) which led to a megahit franchise with two sequels; The Roundup (2022), and The Roundup: No Way Out (2023).