Choi Kang Changmin debuted as the youngest member of the South Korean boy group TVXQ in 2003. In October 2004, they released their first Korean studio album Tri-Angle, which featured the hit lead single Hug. In March 2006, they penetrated the Japanese market with the album Heart, Mind and Soul. In 2009, while the group was at the peak of their popularity, TVXQ members Jaejoong, Yoochun, and Junsu sued SM Entertainment over the supposedly unreasonable length of their exclusive contract. The three eventually left the group and formed the trio JYJ. In 2011, TVQX’s remaining members Choi Kang Changmin and U-Know Yunho made a comeback as a pop duo with the Korean album Keep Your Head Down. In 2015, Choi Kang Changmin released his first Japanese solo mini album Close to You.

Choi Kang Changmin began acting in 2005, but his first major role came in 2011 with the SBS romance drama Paradise Ranch. In 2012, he made his Japanese acting debut in the film Fly With the Gold, which won him Best New Artist at the 22nd Japan Film Critics Awards. In 2015, he joined the main cast of the MBC fusion sageuk Scholar Who Walks the Night.

Choi Kang Changmin enlisted for his mandatory military service in November 2015. He was discharged in August 2017. He married his non-celebrity girlfriend in October 2020. The couple welcomed their first child in October 2022.