Song Won-seok started out as a model before making his acting debut in 2012 through MBC’s mystery fusion sageuk Arang and the Magistrate. He then played small roles in several TV series such tvN’s Entourage in 2016 and KBS2’s Father Is Strange in 2017. He then landed his first main role in the 2017 KBS2 daily series TV Novel: Dal Soon’s Spring, which scored him a Best New Actor nomination at the KBS Drama Awards. In 2019, he joined the main cast of another KBS2 daily drama called Left-Handed Wife. In 2019, he became part of TV Chosun’s time-traveling sageuk comedy Joseon Survival Guide. That same year, he starred in MBC’s No Second Chances. In 2021, he acted alongside Kim Yoo-jung and Ahn Hyo-seop in the SBS fantasy sageuk Lovers of the Red Sky. He next appeared in the SBS series One the Woman, which won him Best Supporting Actor at the SBS Drama Awards. In 2022, he was cast in the hit SBS romantic comedy Business Proposal.