Jang will play charismatic lawyer Choi Kyung-seo, who works at the country's best law firm in the Korean version of the legal drama.
The actor last appeared on TV in 2012 in the 20-episode "A Gentleman's Dignity" on SBS.
The American series premiered in June 2011 on the cable network USA and is in its seventh season at the moment. It is being remade overseas for the first time in Korea.
Along with Jang, actor and singer Park Hyung-sik, a member of boy group ZE:A, has been cast as Koh Yeon-woo, a junior lawyer who works with Choi.
The Korean version is slated for broadcast sometime in the first half of next year. (Yonhap)