Born in Connecticut, John Sharian attended the Taft School in Watertown, Connecticut and later the Kenyon College in Gambier, Ohio, which he left in 1984.

Sharian graduated from the Bristol Old Vic Theatre School in 1991 and began television acting shortly thereafter, appearing in the British sci-fi comedy series Red Dwarf in 1992.

Sharian's film career began in 1994 with his role as one of the leads in Death Machine and later in the American movies Lost in Space and Saving Private Ryan. He also appeared in The Machinist alongside Christian Bale.