Born in Baltimore, Maryland, Charles is an alumnus of the noted Stagedoor Manor Performing Arts summer program in New York. His film debut was in fellow Baltimore resident John Waters’s Hairspray (1988), followed in 1989 by a performance as Knox Overstreet in the classic Dead Poets Society. Mr Charles’s other work includes the made-for-television movies Murder in Mississippi , in which he portrayed murdered Civil Rights activist Andrew Goodman (1990), Norma Jean & Marilyn (1996) and Our America (2002). His other films include Bryan in Don't Tell Mom the Babysitter's Dead (1991), “sexually ambivalent” Eddie in Threesome (1994), Little City (1997) and S.W.A.T. (2003), as well as a cameo role opposite Miss Piggy in Muppets From Space (1999).

In 1998, Mr Charles was cast in the leading role of sports anchor Dan Rydell in the highly acclaimed TV comedy/drama Sports Night.

In 2004, Josh Charles appeared on stage in New York in a revival of Neil LaBute’s The Distance From Here, which received a Drama Desk award for Best Ensemble Performance. Early in his career he received a Festival Week Award for Best Actor in 1986 for the Stagedoor Manor production of Confrontation, in which he portrayed Brian, opposite Renee Weldon. In January 2006 he created the role of Mark in the world premiere of Richard Greenberg's The Well-Appointed Room for the Steppenwolf Theatre Company in Chicago, following this with a short run at the American Conservatory Theater in San Francisco, portraying the cloned brothers Bernard in Caryl Churchill's A Number.

In 2005 Mr Charles appeared in the film Four Brothers, together with Mark Wahlberg. In 2006 he made further cameo appearances in the films The Darwin Awards and Fast Track.

He is a lifelong fan of the Baltimore Orioles baseball team. In 2004/5 and again in 2005/6 he championed a fantasy football draft on the NFL Network.