As well as writing operas and instrumental works, Matthew has experimented with unorthodox ensembles and performance spaces: his King’s Wood Symphony of 2007 for 20 horns and electronics was premiered in a forest in Kent. He has also composed a series of innovative community works combining professional and amateur performers in a dynamic creative process. Matthew’s opera On London Fields (winner of the RPS education award 2005) was described by Stephen Pettitt in The Evening Standard as "unafraid of complexity, even when writing for very young performers. Some of the clashing rhythms and textural layerings are mind-boggling."

Matthew King's recent works include Odyssean Variations (premiered at LSO St. Luke’s by British cellist Natalie Klein and an orchestra of young musicians from the London Borough of Hackney in 2008); the chamber opera Das Babylon Experiment (premiered in the open air in Nuremberg in 2008), Totentango, premiered in 2010 by the London Symphony Orchestra, Blue, a Gershwinesque Rhapsody for piano and orchestra, premiered by the savant pianist Derek Paravicini and the Orchestra of St John’s at the QEH and Velocity, a Hitchcockian tone poem for ensemble with big band, cellos and chorus, premiered by Aurora in 2011. Matthew King is a composition professor at Guildhall School of Music & Drama.