Oh Ji-eun has been active as an actress since 2003, first appearing in short films such as Actor Oh Mi-soon and Dream. In 2006, she made her small screen debut with a bit role in the SBS series Bad Family. In 2007, she was named Best Actress at the Korea Youth Film Festival for the short film Twins. She also received the Special Jury Prize at the 2007 Mise-en-scène Short Film Festival for her work in the said project. In 2009, she became part of the KBS2 family drama Three Brothers. In 2010, she landed a lead role in the KBS1 daily series Smile, Donghae. Both dramas earned her the Best New Actress trophy at the KBS Drama Awards. In 2012, she joined the satire series King of Dramas, which gave her an Excellence Award nomination at the SBS Drama Awards. In 2014, she starred in OCN’s Ghost-Seeing Detective Cheo-yong and in MBC’s Make a Wish. In 2016, she was cast in her first antagonist role in MBC’s weekend series Blow Breeze, but had to bow out midway due to an ankle injury. In 2019, she was nominated for an Excellence Award at the MBC Drama Awards for Golden Garden.

Oh Ji-eun married a Korean-American man in October 2017.