He is subsequently known for starring in the films Maundy Thursday (2006), Jeon Woo-chi: The Taoist Wizard (2009), Secret Reunion (2010), Kundo: Age of the Rampant (2014), The Priests (2015), A Violent Prosecutor (2016), Master (2016), and Peninsula (2020).

Thus began his modeling career, and he appeared on the catwalk for prêt-à-porter collections in Paris such as DKNY, Gucci and Hugo Boss, as well as for the local Seoul Fashion Artists Association (SFAA).

[6] After being cast in the music video for Jo Sung-mo's "I Swear," Gang began taking acting classes, leading to a change in career.

[7] He made his acting debut on television in 2003, playing a doctor with a regional dialect in Country Princess (also known as Funny Wild Girl), and a chaebol's son in Something About 1%.

[11] His two collaborations with auteur Lee Myung-se in Duelist and M further cemented Gang's status as one of the top young actors in Korean cinema,[7][12][13] earning him critical recognition for his stylish flair and diverse choice of roles.

[14] The Choi Dong-hoon film turned into a holiday blockbuster, selling over 6 million tickets over the winter season despite opening in theaters only a week after the release of Avatar in Korea.

[24] In 2014, Gang returned to the big screen in Yoon Jong-bin's period action film Kundo: Age of the Rampant, playing an illegitimate nobleman's son who attempts to destroy a group of Robin Hood-like outlaws in 19th century Joseon Dynasty.

[37] In 2018, Gang played a delivery man framed for the assassination of a politician in Noh Dong-seok's thriller Golden Slumber, based on Isaka Kotaro's novel of the same name.

One of them is Polaris, a drama written by Jeong Seo-kyeong starring Gang and Jun Ji-hyun, which to be directed by Kim Hee-won co-produced by Showrunner and Studio AA.

[51] In October 2024, Netflix released Uprising,[52] the platform’s first original film featuring Gang, produced by Park Chan-wook and directed by Kim Sang-man.

[54] Because of the revelation, Gang issued a public apology, and cancelled his scheduled recording for Vanishing Time: A Boy Who Returned commentary.