[6] He received his primary education via School of the Air lessons under the supervision of his mother, Margaret Morrissey, along with his brother and sister.

In 1985, he became parish priest of Karratha in the Pilbara region of Western Australia, serving workers in the booming iron ore industry in the area.

In addition to his Diocesan roles, Morrissey served as an army chaplain from 1983 until 2016, achieving the rank of lieutenant colonel.

[11] His episcopal ordination was celebrated 28 June 2017, at the Nagle Catholic College gymnasium, in Geraldton, due to St Francis Xavier's Cathedral being closed for interior renovations.

[13] On 1 September 2021, Morrissey announced he had been appointed by Pope Francis to be the apostolic administrator of the neighbouring Diocese of Broome, following the resignation of Bishop Christopher Saunders on 28 August 2021.