Lee joined Fin.K.L after her friend Ock Joo Hyun—the first member to be selected for the group—introduced her to the casting director selecting the group's members. She sang Eco's "Heng Bok Han Na Reul" and was immediately selected to be in the group.
In 2002, the members from the girl group has started individual activities. Lee Jin has long expressed her interest in acting, before her debut she was in MBC's Police People. Subsequently, she was also in the famous sitcom Nonstop (TV series).
In 2005, Lee Jin started to participate in variety program X-man. Lee Jin has expressed and shown that she had grown into a "lady" from her Fin.K.L teenage days via her change of dressing sense as well as hairstyle. In Xman, she was well known for her stiff dance steps, so she had to create new stiff dance steps for the intro dance segment in each episode. She is also known for being Xman's Ulzzang (best/pretty face) as she has been chosen by a lot of male guests to be her couple for the couple game.
In 2010, Lee Jin joined a variety program called Heroes where 12 artists were to compete in games to garner the popular title or will fall into the unpopular group. In this program she carried boring personality but she is a nice and warm hearted person.