Jang Hee-jin began her entertainment career as a fashion model before debuting as an actress in the 2004 MBC sitcom Nonstop 5. In 2006, she acted alongside Go So-young in the horror movie APT. In 2008, she appeared in the action film Rough Cut, which was nominated for Best Film at the 45th Baeksang Arts Awards. In 2011, she played a supporting role in the KBS2 series Myung-wol the Spy. That same year, she portrayed an actress wanting to prove her talent in the MBN musical drama What’s Up. In 2017, she replaced Gu Hye-sun as the female lead in the MBC weekend family drama You’re Too Much, which won her an Excellence Award at the MBC Drama Awards. In 2019, she starred in TV Chosun’s Babel, opposite Park Shi-hoo. In 2020, she joined the main cast of the tvN suspense melodrama Flower of Evil, which was nominated for Best Drama at the 57th Baeksang Arts Awards.

In 2019, it was confirmed that Jang Hee-jin is in a relationship with a non-celebrity businessman.