Known for his versatility, Ju has also garnered acclaim for his performances in the films Asura: The City of Madness (2016), Along with the Gods: The Two Worlds (2017) and its 2018 sequel, The Spy Gone North (2018), Dark Figure of Crime (2018), and Ransomed (2023).

[citation needed] In 2003, Ju debuted as a model, in advertisements for clothing brands such as Calvin Klein, Levi's and Reebok.

He had various bit parts in television dramas, but it was in 2006's romantic comedy Princess Hours, based on the manhwa Goong, that he achieved breakthrough.

The drama was a hit domestically with a peak rating of 28.3%, and internationally across Asia, catapulting Ju into Korean Wave stardom.

[11] In January 2011, ahead of Ju's military discharge in November, he signed with entertainment agency KeyEast, owned by actor Bae Yong-joon.

[19] In 2014, Ju was paired up with Ji Sung and Lee Kwang-soo in Confession,[20] a neo-noir film that brutally explores the aftermath of three men's friendship after the death of one's mother.

[23] In 2016, Ju starred in the noir crime thriller Asura: The City of Madness, which premiered globally at the 41st Toronto Film Festival.

[40] On February 2, 2010, Ju enlisted in the Republic of Korea Army to serve his mandatory military service for five weeks of basic training at 306th draft in Uijeongbu of Gyeonggi Province, followed by active duty with the reserve forces.

Ju's lawyer also stated, "Of course he must accept the price of his crime, but wrong information kept coming out and exaggerated him as a habitual user, and some of it was unfair.