Creasy has studied and performed music since he was a child, most notably with his mentor, jazz luminary Peter Erskine. He attended California Institute of the Arts, studying in the jazz program headed by Charlie Haden, and he has recorded at Interscope / Geffen Records and Capitol Studios, Hollywood. Current projects include Carry On, Troubadours with singer Sadhbh Burt Fitzgerald. Together they play original material as well as standards of both American and Irish roots music. Sadhbh and Jonathan are touring members of the Great War Road Show, produced and hosted by Myles Dungan of RTÉ Radio.
Creasy recently co-produced a recording of Benjamin Dwyer's imagines obesae et aspect ingratae, a piece for solo viola performed by the world-renowned Garth Knox.