'[His] is a style that seems to manage to have it both ways, preserving the expressive possibilities and archetypes of the Scottish folk tradition within an idiom that can call on techniques and technology from the whole modernist tradition since 1945.'
Andrew Clements, The Guardian

William Sweeney was born in Glasgow, educated at RSAMD and then at the Academy. He is Emeritus Professor of Music at the University of Glasgow.

He has been commissioned by the BBC, Paragon Ensemble, St Magnus Festival, Musica Nova, Capella Nova, Mayfest, the STUC, RSAMD, McNaughten Concerts, Theatre Cryptic and the Jim Henson Organisation.

His Sonata for Cello and Piano won a BASCA/Radio 3 British Composer Award 2011. Recent works include: These Lands, This Wall (Lammermuir Festival, 2012); Absence for Wind, Strings and Percussion (Sound Festival Musique Desmesurées, Aberdeen and Clermont-Ferrand, 2014) and Eolas nan Ribheid (The Wisdom of the Reeds), a clarinet concerto commissioned in 2016 by the BBC and performed for broadcast in 2017 by the BBC Scottish Symphony Orchestra, soloist Yann Ghiro. William's latest work Westlin Winds is a concerto for bass-clarinet and strings, performed in April 2022 by Sarah Watts and the Glasgow Barons.

William was a member of the Executive Committee of the Musicians' Union from 1989 to 2004, acting as Chair of its Executive Committee in 2003. He is also a retired member of the Board of The Ivors Academy (formerly the British Academy of Songwriters, Composers and Authors).