The role was previously played by Jennifer Garner in 2003's "Daredevil, The Movie" and 2005's "Elektra" movie, reported Aceshowbiz.
Yung's Elektra is described as "a mysterious woman from Matt Murdock's (Charlie Cox) past whose dangerous and exotic ways may be more than he can handle."
She was referenced in season one when Matt told Foggy (Elden Henson) that things "didn't work out" with a certain Greek girl.
She joins Jon Bernthal, who was previously added to the cast for the season to play The Punisher.
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He is a vigilante, who aims to clean up New York City's Hell's Kitchen by any means necessary, no matter how lethal the results.
Production for the second season is currently underway for a 2016 premiere.
Recently, Cox and Henson were spotted filming a scene in East Harlem. Rosario Dawson will also reprise her role as Claire Temple, and Deborah Ann Woll is expected to be back as Karen Page.