Born as Kim Hyung-soo, he began his career in entertainment after starring in a music video alongside older sister, Actress Kim Tae-hee. Using the stage name Lee Wan, he made his acting debut in 2003. He first drew notice in a supporting role in the television drama Stairway to Heaven, followed by leading roles in romantic comedies Snow White: Taste Sweet Love and Let's Go to the Beach. He reunited with Stairway to Heaven costar Park Shin-hye in 2006 in the melodrama Tree of Heaven which was a joint Korean-Japanese production. Lee also contributed the song "Where Farewells Don't Exist" to the drama's Soundtrack.