Sohn Seung-won started acting on stage, appearing in several musicals such as A Person Who Dreams in 2010 and Welcome Mom in 2011. In 2013, he was cast as Hedwig in the Korean production of Hedwig and the Angry Inch, making him the youngest Korean actor to bag the said role. In 2014, he played supporting characters in Sweet Secret and Healer, which both aired on KBS2. In 2016, he starred in the MBC daily series Person Who Gives Happiness. That same year, he became part of the JTBC campus drama Age of Youth and then returned for its second season in 2017. In 2018, he joined the main cast of the first season of the JTBC youth comedy Woohoo Waikiki.

Due to his repeat driving under the influence offenses, Sohn Seung-won was sentenced to eighteen months in prison in 2019. This disqualified him from rendering military service.