Oh Dae-hwan began his acting career playing mostly supporting roles in films like 2004’s A Crimson Mark and 2007’s Giraffe & Africa. He landed his first television role in the 2010 MBC epic war drama Road No. 1. In 2011, he starred in the short film Jihye’s Fable, which won him the Special Jury Prize for Acting at that year’s Mise-en-scène Short Film Festival. In 2015, he appeared in the MBC weekend series Queen’s Flower and in the made-for-television drama film I’m After You. In 2016, he joined the OCN cop comedy drama Police Unit 38 as well as the hit SBS legal series Defendant in 2017. In 2019, he acted alongside Kim Dong-wook in MBC’s Special Labor Inspector Jo, which won him Best Supporting Actor at the MBC Drama Awards. In 2020, he was once again named Best Supporting Actor at the KBS Drama Awards for the family drama Once Again. In 2021, he acted alongside Junho and Lee Se-young in the MBC sageuk The Red Sleeve Cuff, which gave him a Best Supporting Actor nomination at the MBC Drama Awards.

Oh Dae-hwan attended Korea National University of Arts.