Donagh Brendan O'Malley was born 1921 in Limerick City. He was educated at University College Galway and qualified as an engineer in 1943. He worked as an engineer in Limerick until 1954 when he was elected to Dáil Éireann as a Fianna Fáil TD. In 1961 he became Parliamentary Secretary to the Minister for Finance. In April 1965 Sean Lemass appointed him Minister for Health. The following year, 1966, he became Minister for Education. O'Malley is credited with introducing free post-primary education and free school transport. His plans to merge Trinity College Dublin and University College Dublin aroused huge controversy, despite being supported by his Cabinet colleague Brian Lenihan.
Donagh O'Malley died suddenly in Limerick on 10 March 1968 before his vision for the education system was completed. His nephew, Desmond O'Malley was elected in his place.