Philip Cashian's music has been commissioned, performed and broadcast worldwide: recent performances have included the Ojai Festival (California), Musikmonat (Basle), the St Paul Chamber Orchestra, the Esprit Orchestra (Toronto), Aldeburgh Festival, Spitalfields Festival, Huddersfield Contemporary Music Festival and the BBC Proms as well as performances in Germany, France, Spain, Austria, Hungary, Holland, Greece, Denmark, Sweden, New Zealand and China.

Among his many commissions are: Night Journeys (1998), a double concerto for timpani and percussion for the London Symphony Orchestra; Spitbite for the Britten Sinfonia; Io for the BBC National Orchestra of Wales; Three Pieces for chamber orchestra and Skein for Birmingham Contemporary Music Group; and Tableaux, which the Northern Sinfonia commissioned for the 2003 BBC Proms and for their European tour.

In 2006 Sarah Nicolls gave the first performance of his Piano Concerto with the London Sinfonietta under Zsolt Nagy, while in 2008 Cashian was again commissioned by the Sinfonietta to write The Opening of the House for their inaugural concert at Kings Place, London. 2008 also saw the premiere of his first opera, The Cumnor Affair, for Tete-a-Tete Opera Company at the Riverside Studios, London.

Works for smaller forces include A Sea of Tales for Melinda Maxwell and Endymion, So Lonely for Mary King and the Kreutzer Quartet, and pieces for the Haffner Wind Ensemble, Pittsburgh New Music Ensemble, The New Music Players, Paul Watkins, Alan Hacker and the Schubert Ensemble. He has also worked with the choreographer Ian Spink and written for The Knack at ENO studio. He has a close relationship with the Composers Ensemble for whom he has written, to date, half a dozen pieces. Future projects include new works for soprano Claire Booth and a Cello Concerto for Robin Michael.

In 2004/05 he was the composer in residence at the Centre for Young Musicians and has written numerous pieces for children and amateur musicians; and in June 2007 Philip Cashian became Head of Composition at the Royal Academy of Music.