Lee made her acting debut in 2003, and among her early roles were in People of the Water Flower Village (2004) opposite Song Il-gook,[7] and as the antagonist in Save the Last Dance for Me (2004).

[8] In 2005, Lee played her first leading role in the daily drama My Sweetheart, My Darling,[9] followed by the Silla-set historical epic Ballad of Seodong with Jo Hyun-jae.

[10] She spent the next several years in television dramas — Mr. Goodbye with Ahn Jae-wook,[11] Queen of the Game with Joo Jin-mo,[12] and Becoming a Billionaire with Ji Hyun-woo[13] — but none struck a chord with audiences or critics.

The heist comedy is set during colonial rule in the 1940s, and she and Park Yong-woo played notorious swindlers out to steal a diamond from the Japanese army.

In More Than Blue, Lee plays the soulmate of a terminally ill man (Kwon Sang-woo), but their love ends in a tragedy undercut with a poetic sparseness.

[17][18] While in I Am Happy, Lee played a nurse who falls for a patient in the psychiatric ward (Hyun Bin), and in each other they find consolation to see them through their harsh and miserable reality.

[23] She then played the titular character in Seoyoung, My Daughter (2012–2013), a career woman who is angry at her father (Chun Ho-jin), whose gambling addiction led to her mother's death, yet she struggles to keep the family together and make ends meet.

[31][32] In 2017, Lee starred in SBS legal thriller Whisper,[33] playing the role of a section chief of criminal division who gets dismissed from the police and later on disguise herself and work as an undercover at a law firm.