Norman Thomas Gilroy was born in Sydney on 22 January 1896 to William James Gilroy and Catherine Slattery. He was educated at St Benedict's School Broadway, and Marist Brothers' College, Kogarah.
He was a veteran of the Gallipoli campaign of 1915.
He attended Seminary at St Columba's Springwood, and Propaganda Fide, in Rome. He was ordained a priest on 24 December 1923 at St John Lateran Basilica, Rome, by Cardinal Van Rossom.
He served as the Secretary to the Apostolic Delegation, 1924 and Chancellor and Diocesan Secretary for Lismore Diocese, 1931.
Elected Bishop of Port Augusta on 10 December 1934 and consecrated on 17 March 1935 at St Mary's Cathedral, by Archbishop Philip Bernadini.
Promoted Archbishop of Cypsela In Partibus Infidelium and coadjutor cum jure successionis of Sydney on 1 July 1937. Succeeded to the Archdiocese of Sydney on 8 March 1940.
Created Cardinal on 18 February 1946, the first Australian-born member of the Sacred College.
Created Knight Commander of the British Empire 1969, the first Cardinal to be knighted since the Reformation, and he was Australian of the Year in 1970.
Resigned as Archbishop on 9 July 1971.
Cardinal Gilroy died on 21 October 1977.