Proinnsías Ó Duinn was born in Clontarf in Dublin. He studied cello, piano and conducting at the College of Music, Dublin and began composing at the age of nineteen. In 1963 he was appointed conductor of the Iceland Symphony Orchestra and then principal conductor and music director to the National Symphony Orchestra of Ecuador. Following his return to Ireland he joined RTÉ, Ireland’s national radio and TV station, in 1974 as conductor of the RTÉ Singers and later became principal conductor of the RTÉ Concert Orchestra until 2003.
His compositional output features chamber works as well as arrangements for television, theatre and film. In 1997 his musical, Stuff and Nonsense, based on the life and writings of Edward Lear, was premiered in Dublin's National Concert Hall.