Esom made her entertainment debut in a model selection program on Mnet in 2008. She then began her acting career in 2010 with a role in the film Second Half. In 2014, she starred as lead in the thriller movie Scarlet Innocence, opposite Jung Woo-sung. Her performance in the film earned her the Best New Actress trophy at the 15th Director’s Cut Awards. Additionally, she scored four more Best New Actress nominations from different award-giving bodies for her work in the movie. In 2017, she appeared in the historical film Warriors of the Dawn, in which she was nominated for Best Supporting Actress at the 54th Baeksang Arts Awards. Also in 2017, she headlined the drama movie Microhabitat, which won her numerous Best Actress citations, including one from the 19th Busan Film Critics Awards. In 2019, she was nominated for Best Supporting Actress at the 29th Buil Film Awards for My Exceptional Brother. In 2020, she once again showcased her award-winning acting chops in the comedy drama film Samjin Company English Class.
Esom shared in an interview that her agency director thought her face looked like a som-mungchi or a cotton ball. This is why she was given her stage name Esom, which is a combination of her surname Lee and som from the word som-mungchi.