Oh Seung-yoon began acting as a child, making his first notable appearance in the 2001 SBS sageuk Ladies of the Palace. His work in the series won him Best Young Actor at the SBS Drama Awards. In 2002, he starred in the KBS2 children fantasy drama Magic Kid Masuri, which earned another Best Young Actor trophy at the KBS Drama Awards. In 2006, he became part of the smash hit MBC sageuk Jumong. The following year, he played the young counterpart of Oh Kwang-rok’s character in another top-rating MBC sageuk Legend. In 2009, he was cast in the KBS2 series The Princess Has Returned, which scored him a Best Young Actor nomination at the KBS Drama Awards. In 2014, he joined the 13th season of tvN’s long-running office comedy Rude Miss Young-ae. In 2018, he portrayed Shin Sung-rok’s younger brother in SBS’s An Empress’s Dignity.

Oh Seung-yoon attended Hanyang University’s theater and film department. He enlisted for his mandatory military service in September 2019.