O'Sullivan attended the state school in Taringa before completing his education at St. Joseph's Nudgee College. He followed his father into the legal profession, serving articles of clerkship with firms in Brisbane and Warwick. He did not attend law school but was admitted as a solicitor in December 1922 by examination.[3] He subsequently took over his father's practice in Brisbane, later forming a partnership with John Joseph Rowell.[2]
Regarded as "a leader of Brisbane's mercantile sector", O'Sullivan was president of the Brisbane Chamber of Commerce from 1936 to 1937 and the Property Owners' Protection Association from 1937 to 1938.[3] He served in the Royal Australian Air Force from May 1942 to December 1944, performing intelligence and administration in Australia and the South-West Pacific.[2] He was commissioned as a flying officer and met future prime minister John Gorton while stationed at Milne Bay.[3]
In his maiden speech to parliament, O'Sullivan spoke of his belief in the doctrine of natural rights deriving from God. He was a social conservative, supporting heavy censorship as a safeguard against "indecency, blasphemy and sedition". Although he voted for the Matrimonial Causes Act 1959, which established uniform national divorce laws, he believed that divorce violated the divine law and stated that "a valid consummated Christian marriage is indissoluble". He was an anti-communist and cited the papal encyclical Quadragesimo anno in a 1947 speech against the Chifley government's bank nationalisation bill.[3]
Personal life
O'Sullivan married Jessie McEncroe on 3 April 1929, with whom he had two sons.[2] He was a devout Catholic and was a close connection of Archbishop James Duhig, with his biographer Duncan Waterson stating that "on matters of faith, morals, censorship and conservative Catholic social thought the two were as one".[3] O'Sullivan was made Knight Commander of the Order of the British Empire in 1959.[2]
O'Sullivan died unexpectedly of a coronary occlusion while visiting Sydney in 1968.[4] He was survived by his wife and two sons. He was accorded a state funeral and was buried in Nudgee Cemetery.[2]