Known best for his work with the Korean rock band F.T. Island, Seung-hyun also pursued a career as a stage and screen actor, appearing in an episode of Style and in a stage musical inspired by the Jack the Ripper murders.
Early in his career, he performed on a variety program called Idol Maknae Rebellion.
Though primarily a guitarist, he also contributed vocals to "I Believe Myself" and several other F.T. Island tracks.
He was born and raised in Seoul, South Korea.
He and fellow F.T. Island guitarist Choi Jong-hoon both participated as models in Seoul's Autumn 2009 Fashion Week.