Devine was born in County Galway in 1970. He has played supporting roles in several films. Devine graduated with honors from Trinity College Dublin, where he studied philosophy and sociology. Since then he has built a career as an actor in both film and on stage. His credits include numerous theatrical roles, including in various works by Shakespeare. In the 1990s, Devine appeared in the rural drama Glenroe as Ray O'Driscoll, who fled the country after killing his brother Oliver in 1999. This storyline became one of the most significant in the series' history in the 1990s.

Among his film roles is the Irish criminal Gerry "The Monk" Hutch in the film Veronica Guerin. He gained recognition for his work in several other films and television series, including King Arthur, Nora, Guesthouse (where he played the lead role), The Tudors, Vikings, and The Gift.

Devine appeared in a Guinness television commercial, playing the role of Tom Crean, the legendary Arctic explorer from County Kerry.

He subsequently appeared in the Irish soap opera Fair City as Louis Gleeson. In 2010, Devine performed on stage in the play My First Time alongside Lee Arnold, Alan Short, and Claire Tully at various venues across Ireland. He played the Earl of Kent in the recent Netflix series Vikings: Valhalla.