As a student of theatrical training, Sam O'Mahony attended the London Academy of Music and Dramatic Art (LAMDA). After graduation, Sam moved quickly into work for the Royal Shakespeare Company. During the Company's Complete Works Festival, Sam appeared in three different productions. Sam O'Mahony has continued to make use of his classical theatre training, mostly appearing in London productions. His repertoire expands into the small screen world as he appeared across television also. Beginning in 2007, he appeared on Casualty (1986) (TV). Four years later, in 2011 Sam would make his second television appearance in the Syfy original movie Ferocious Planet (2011) (TV) as a Senator's aide to actor John Rhys-Davies. Next, he landed on an episode of the short-lived fantasy series drama Camelot (2011) (TV). In addition to his stage and television work, Sam has lent his talent to voice work offering what has been described as having a baritone range, yet youthful delivery. Although finding his success in London, Sam returned home to Dublin, Ireland with intent of expanding his success and happiness both on and off the stage and screen.