[2] After practising at the Irish Bar in Dublin, O'Connor spent time as a critic before turning to writing.
His work spanned areas such as biography, poetry, Irish history, drama, diary, and literary criticism.
He was a well-known intellectual figure in contemporary Irish affairs and expressed strong opinions against censorship and the war on drugs.
He was also known for the autobiographical The Ulick O’Connor Diaries 1970-1981: A Cavalier Irishman (2001), which details his encounters with well-known Irish and international figures, ranging from political (Jack Lynch and Paddy Devlin) to the artistic (Christy Brown and Peter Sellers).
[5] O'Connor's great-grandfather was Matt Harris, Land Leaguer, Fenian, and Irish Parliamentary Party Member of Parliament.