Lee debuted as a professional player in 2004, at the age of 16, passing the intense competition that selected one new female pro annually. As a professional player, she was often listed among the top female players in Korea. She won 1st place in the women’s division of the 5th ETLand Cup Professional Baduk Championship in 2008, and won a bronze medal at the 2008 World Mind Sports Games in the same year. She qualified 4 times for the Korean national team (2006, 2007, 2008, 2010), which selects 5 female professional players each year for the Jeongganjang Cup international women’s team championship.