Kang Hye-jung started modeling when she was in high school. She then forayed into acting by appearing in minor roles in television dramas and sitcoms. In 2001, she landed her first film role in the arthouse movie Nabi, in which she won Best Actress at that year’s Puchon International Fantastic Film Awards. She next appeared in the award-winning revenge thriller film Oldboy, in which she picked up several acting awards including Best Supporting Actress at the Blue Dragon Films Awards. In 2005, she once again showcased her acting skills in the movies Rules of Dating and Welcome to Dongmakgol. She took home the Best Actress trophy at the 2005 Busan Film Critics Awards for her performance in Rules of Dating. For her work in Welcome to Dongmakgol, she received three Best Supporting Actress awards. The comedy movie, which was set during the Korean War, was also chosen as South Korea’s official entry to the 2005 Academy Award for Best Foreign Language Film. In 2011, she starred in the US-Korean co-production movie Wedding Palace, opposite Japanese-American actor Brian Tee.

Kang Hye-jung married Epik High member Tablo on October 26, 2009. They welcomed their daughter on May 2, 2010. Kang Hye-jung also dated actor Jo Seung-woo from 2004 to 2007. In 2006, the couple starred in the romantic drama film Love Phobia.