Choi Kang-hee made her acting debut in 1995 with the high school drama The New Generation Report: Adults Don’t Know, then went on to appear in the horror film Whispering Corridors (1998) and television series such as School (1999), Sweet Buns (2004), and Our Stance on How to Treat a Break-up (also known as Rules of Love, 2005).

In 2006, Choi starred in the low-budget black/romantic comedy film My Scary Girl, which became a critically praised sleeper hit.She continued to receive good notices for her roles in the television series My Sweet Seoul (2008), Protect the Boss (2011), Goodbye Mom (2009), and Petty Romance (2010).

In addition to her acting, Choi is a radio DJ on KBS Cool FM. She also has her own clothing brand, Nowhere333.

In October 2006, Choi was awarded a silver medal by the Korea National Red Cross in recognition of her frequent blood donations. A year later she became the first Korean celebrity to donate bone marrow, having pledged as a donor in 1999.

Choi signed with KeyEast in 2007, but after her contract ended in June 2014, she joined new management agency Will Entertainment.