Kim Seo-hyung made her acting debut in the KBS2 series Tomorrow’s Love in 1994 and has since graced both the big and small screens in her home country. Her career breakthrough came in 2008 when she played an evil mistress in the hit SBS revenge drama Temptation of Wife, which won her an Excellence Award at the SBS Drama Awards. In 2014, she starred in the award-winning romance melodrama film Late Spring. She was named Best Lead Actress in a Foreign Language Film at the 3rd Madrid International Film Festival for her performance in the movie. In 2017, she appeared in the action film The Villainess, which had its world premiere at the 70th Cannes Film Festival. In 2018, she joined the main cast of the top-rating JTBC series SKY Castle, which scored her the Best Supporting Actress trophy at the 24th Asian Television Awards. Her work in the series also earned a Best Actress nomination at the 55th Baeksang Arts Awards. In 2020, she received a Top Excellence Award at the SBS Drama Awards for her leading role in Nobody Knows.

Kim Seo-hyung studied liberal arts at Yeongdong Women’s College.