Ramsay's screen debut was opposite fellow Montrealer Elias Koteas in the film Malarek (1988). Ramsay and Koteas went on to appear in two other films together, Hit Me (1996), and Collateral Damage (2002). Ramsay's first lead in a major motion picture came when he was cast as Carlitos Paez in Director Frank Marshall's film Alive (1993), the biographical survival drama based upon Piers Paul Read's 1974 book Alive: The Story of the Andes Survivors, which detailed the story of the Uruguayan rugby team that crashed into the Andes mountains.
In 2011 Ramsay made his directorial debut with Hamlet (2011). Ramsay also produced, wrote the adaptation, and starred as Hamlet. Hamlet premiered in competition at the Vancouver International Film Festival in 2011.
Ramsay appeared as the jaded house boy Carlucci opposite Michael Douglas and Matt Damon in Behind the Candelabra (2013), directed by Steven Soderbergh, about the last ten years in the life of Pianist Liberace. Behind the Candelabra marked the second time that Ramsay had worked with Soderbergh. In 1995, Ramsay appeared in The Professional Man, part of The Showtime film noir series Fallen Angels, starring opposite Peter Coyote and Brendan Fraser.
