Dunsworth studied acting at the University of Guelph, but dropped out in his fourth year. He went on to act in numerous CBC radio dramas, and had starring roles in many stage productions at the Neptune Theatre in Halifax. In 1970, Dunsworth leased an abandoned building on Halifax's waterfront, and converted it into a playhouse. Dubbing it the Pier One Theatre, it became the city's first and most successful alternative theater production house. In the late 1980s, Dalhousie University hired Dunsworth to produce the university's Welcome Show for new students at the Rebecca Cohn Auditorium, in which he also occasionally had an unseen voice-over role. In 1987, Dunsworth founded Filmworks Casting where he worked as Halifax's most renowned casting Director. Dunsworth met Director Mike Clattenburg in the mid-1990s when he tried out for a bit part in Clattenburg's film short, One Last Shot. Dunsworth's small role gradually transformed into a leading part that earned him a Best Performance award from the Atlantic Film Festival. From there, he further developed the character into what would eventually become Jim Lahey in Trailer Park Boys.