His father deserted the family when he was a child and he was mainly educated by his mother Mary Ann who was the daughter of Edward Burgoyne, a soldier of the 63rd regiment (born Derry, Ireland c.1794) by his wife Catherine Cruise.
He started as a printer's devil on the Hobart Mercury but, being bright and intelligent, graduated at the desk, and became, when still young, a reporter for that paper.
In 1884 O'Sullivan was part of a land reform conference, which included Paddy Crick, Louis Heydon and Adolphus Taylor to "establish a political organisation of the agricultural, mining, and working classes of New South Wales, in order to initiate a more liberal and progressive policy for the colony", a protectionist party that became known as the Land and Industrial Alliance,[3] which was for a time more successful.
[2] In 1909 he became the third President of the New South Wales Rugby League in the year after incumbent secretary and founding father of the game Henry Hoyle resigned.
He first stood for the legislative assembly for the district of West Sydney, at the 1882 election but was unsuccessful with a margin of 549 votes (3.9%).
[7] In September 1899, O'Sullivan became Secretary for Public Works in the Lyne ministry, and held the same position when John See became Premier until June 1904.
[1] He was elected an alderman on the City of Sydney for Cook Ward in December 1906, serving until his death in April 1910.
[2][10] He published during the 1890s Esperanza: a Tale of Three Colonies, and in 1906, Under the Southern Cross: Australian Sketches, Stories and Speeches.