She rose to fame in the 2002 sitcom Nonstop 3, and has since played leading roles in the television series Something About 1% (2003) and Snow White: Taste Sweet Love (2004), as well as the films Spy Girl (2004) and The Elephant on the Bike (2007).

This was followed by her first film Spy Girl (2004), a comedy about a North Korean agent who goes undercover in the South as a Burger King employee, but to her dismay finds herself becoming popular with the male student customers.

[8] In 2012, Kim starred in Solid but Fluid (titled "Silverscreen Lovers" in Korean), a 3D short film about a soon-to-be-married couple that catches a glimpse of their future while at the drive-in theater.

[9][10] Kim published a book of essays in 2012, which included her musings on life as an actress, as well as stories about her volunteer work helping impoverished children as part of the fight against global hunger.

[14][15] They first met when both became goodwill ambassadors for the humanitarian organization Food for the Hungry International, and grew close when Yoo composed the music while Kim wrote the lyrics for the single "Hello, Agnes!"