Puw's works include pieces for unusual combinations of instruments, such as a tuba quartet or a trio consisting of harp, cello and double-bass, as well as more traditional forces such as solo baritone and piano, choir or orchestra. He was associated with the BBC National Orchestra of Wales as its Resident Composer, the first holder of this title, from 2006 to 2010. Puw's own Welsh identity is a recurrent theme in his music: some of his pieces set Welsh-language poetry to music and one of his pieces, "Reservoirs", is written about the flooding of Welsh valleys to provide water for England.