Yoon Kyun-sang initially worked as a model before becoming an actor. He made his acting debut in 2012 with a supporting role in the SBS fusion medical sageuk series Faith. His big break came two years later when played the older brother of Lee Jong-seok’s character in the hit SBS series Pinocchio. In 2015, he became part of the SBS dramas The Time I’ve Loved You and Six Flying Dragons, which won him the New Star Award at the SBS Drama Awards. His performance in the latter also earned him the Best New Actor trophy at the 23rd Grimae Awards. In 2016, he appeared in the SBS medical romance Doctors, in which he was named Best New Actor at the 5th APAN Star Awards. He was also nominated for an Excellence Award at the 2016 SBS Drama Awards for his performance in the series. In 2017, he landed his first leading role in the MBC sageuk Rebel: Thief Who Stole the People, which was hailed Drama of the Year at the 36th MBC Drama Awards. His work in the series also scored him several acting nominations.

Yoon Kyun-sang enlisted for his mandatory military service before his debut as an actor. He was discharged in 2010.