However, the group soon fell by the wayside due to fierce competition among manufactured bands, which led to one of the members quitting before they completely disbanded in 2003.

was dissolved, Seo attended Dongduk Women's University, where she majored in applied musicology to keep her dream of a singing career alive.

[4] Supporting roles followed in the period drama Hwang Jini (2006),[5] TV police procedural H.I.T (2007),[6] and the queer-themed film Ashamed (2011).

[15][16] Seo said the character that most resembled her real-life personality was the foodie freelance writer in Let's Eat 2 (2015), adding that she "didn't realize how much fun shooting a lively and comedic drama could be.

[19] Her popularity grew rapidly after the hit romance comedy drama Another Miss Oh (2016), in which she starred alongside Eric Mun.

[24] In 2018, Seo was cast in the fantasy melodrama The Beauty Inside which was based on the 2015 romantic comedy film of the same name.

In 2022, Seo starred in the SBS legal drama Why Her in the titular role of Oh Soo-jae, a lawyer-turned-professor[29] and in the film Cassiopeia as a woman who is diagnosed with Alzheimer's disease and is slowly turning into a young child due to the loss of her memory.