Wirth attended Collegiate Prep School in Manhattan and Brown University in Providence, Rhode Island. Discovered by photographer Bruce Weber while at Brown University, he started modeling in New York City in the mid 80s for such magazines as Seventeen, GQ, Interview, and teen magazines.
While at Brown he did his first Diet Pepsi Commercial before moving on to television and movies. His first television show was The Equalizer and moved to LA to start an acting career. His first movie was Seven Minutes In Heaven.
Fifteen years later he is fine tuning his craft and has moved on to being behind the camera. Besides acting, he is also serious about writing,directing,and his artwork is showing in many California galleries. Having completed a Short Film, Kismet, in 1999, he moved on to his first full length Independent film, MacArthur Park, for which he was the writer, director and producer. The film was screened at the Sundance Film Festival 2001 (Grand Prize nominee), Taos Talking Picture Festival (Land Grant nominee), and Seattle International Film Festival 2001 as part of the Black Experience in Films.
In the early 1990s Billy fronted a rock band in LA called Dust N'Bones. He works off and on with a band called "The Cronies" and they are still in the working stage of a new acoustic CD with music written by Wirth and Steven Costentino.
Billy seems to have found his calling behind the scenes of movie making and at the present time is working on a documentary that combines the plight of the homeless, one of Billy's long time interests, and behind the making of MacArthur Park. He changed management in 2003 by going with Creative Management Group of Beverly Hills and will be working with agents looking for acting and directing projects. In 2003 he also opened his own online Art Gallery and completed a new film The Drone Virus, plus a feature for director Andrew Wagner called The Talent Given Us.