From his beginnings as a NY street musician, Geoffrey rose to play on-stage violin and percussion in the Broadway and road productions of M. Butterfly, with Tony Randall, and to perform and tour with Imago Recording artist Suzanne Rhatigan. Along the way, he also managed to sit in with folks like Buddy Miles, Jimmy Buffett, Ann and Nancy Wilson and Heart, Alan White (John Lennon and YES) The Meters, Bireli Lagrene, Don Peake, and he was co-founder of the NY jump blues band Groovalaya - playing violin along with a tenor sax to create the sound of a jump blues horn section with two instruments.

Geoffrey's strong suit has always been live performance, which led to his recent solo appearances at the Triple Door Theater, Benaroya Hall, Microsoft's World Government Leaders Conference in Seattle, and the lavish Samsung booth at COMDEX and CES in Las Vegas. As a session violinist and soloist, Geoffrey has been featured on the soundtrack to the Paramount pictures release The Gift with Cate Blanchett, the A&E production of PT Barnum, with Beau Bridges, and Wooly Boys with Kris Kristopherson and Peter Fonda.

Close to his home in Seattle, Castle is a regular and welcome feature on independent and NPR radio stations throughout the Northwest with a large and loyal following. Constant performing and touring has drawn over 7,000 people at current count to sign up to receive his bi-weekly newsletter online.

The founder of festival favorite world music group the Guarneri Underground, Castle still relishes his role as a band leader with an illustrious list of band alumni that include Roger Fisher, Mike Derosier, and Steve Fossen from the original line-up of the multi-platinum Northwest supergroup Heart, and Beth Quist who is currently the featured vocalist for the Cirque du Soleil production of KA at the MGM Grand in Las Vegas. Beth and Roger were both featured on Castle's 2002 production Wander This World which received airplay on over 500 radio stations nationwide, debuted at #12 on the New Age/World charts and won “Best Celtic Song” at the 2004 J.P.F. awards in Los Angeles. His lastest group features Mark Cardenas on Keys who was part of Morris Day and the Time in the movie Purple Rain, Davey C. on drums (Eek-a-mouse), and Lennox Holness on bass. This group packs the dance floor with a mix of celtic, funk, blues, bluegrass, reggae and classic rock that is truly groundbreaking if only in its breathtaking variety.

Geoffrey Castle is a pioneer on the electric violin, developing one of the first truly user-friendly warm sounding six-string violin designs with Tucker Barrett and company in the 1990's. Redefining the role of the violin in popular music has been a major theme of Castle's career, and with his latest release “Mist on the Mountain” he brings together the mastery and artistry of an instrument with ancient roots, in combination with the latest in modern technology in a breathtaking and riveting performance.