Born and raised in the small town of Diana, West Virginia, Josh attended West Virginia Wesleyan College then transferred after a year to West Virginia University where he graduated with a business degree in marketing.
Josh got his start doing local theater at the Landmark Theatre in Sutton, West Virginia, and eventually moved to New York where he studied at the T. Schreiber Studios (and was a company member of the 13th Street Repertory Theatre). He then moved to Los Angeles and performed on stage in Light Bulb and Beacon (which also starred Robert Forster and Brooke Shields).
In addition, Stewart also had a part in the independent film Jekyll and won a co-starring role in his first pilot Then Came Jones.
He has appeared in the television show CSI, and in a starring role on the police drama Third Watch. As of March 2007 he plays a Hollywood actor named Holt McLaren on the drama Dirt.