Lee Se-young started out as a child actress, debuting at the age of five in the 1997 SBS series The Brothers’ River. In 2004, she starred in the drama film When I Turned Nine, which won her Best Young Actress at the 12th Chunsa Film Art Awards. In 2005, she was nominated for Best New Actress at the 41st Baeksang Arts Awards for her role as a headstrong elementary student in the comedy movie Lovely Rivals. In 2016, she was able to show her mature side in the KBS2 family drama Laurel Tree Tailors, which earned her the Best New Actress trophy at the 53rd Baeksang Arts Awards. In 2019, she appeared in the tvN sageuk The Crowned Clown and  in the SBS medical drama Doctor John. In 2021, she acted alongside Junho in the high-rating MBC sageuk The Red Sleeve Cuff, which gave her a Top Excellence Award at the MBC Drama Awards.

Lee Se-young attended Sungshin Women’s University.