Kim Sae-ron began her career as a child actress through a leading role in the 2009 film A Brand New Life, which earned her several Best New Actress trophies including one from the 19th Buil Film Awards. The young actress also attended the 2009 Cannes Film Festival for the special screening of the movie. In 2010, she acted alongside Won Bin in the action thriller film The Man from Nowhere, which scored her a Best New Actress nomination at the 47th Baeksang Arts Awards. In 2013, she took home the Best Young Actress honors at the MBC Drama Awards for Queen’s Classroom. In 2014, she starred in the drama film A Girl at My Door, which won her Best New Actress at the 35th Blue Dragon Film Awards and the 2015 Golden Cinematography Awards. For the second time, she attended the Cannes Film Festival after the movie was invited to the 67th edition’s “Un Certain Regard” section. She was then named Best Foreign Actress at the 24th China Golden Rooster & Hundred Flowers Film Festival for her performance in the 2015 historical drama film Snowy Road. In 2016, she was cast in her first adult lead role in the JTBC sageuk series Mirror of the Witch.

Kim Sae-ron’s younger sisters namely Ah-ron and Ye-ron are also actresses. In 2018, Kim Sae-ron was accepted to Chung-Ang University’s Department of Performing Arts and Film Studies.