O’Conor was descended from the ancient kings of Connaught through a younger son of Sir Hugh O’Conor Don (1541-1632) of Ballintubber Castle, sometime Member for county Roscommon. His grandfather Charles O’Conor (1710-91) was a noted antiquary and his father Denis and uncle Charles (1736-1808) of Mount Allen, as heirs to one of the oldest and most extensive Irish landholding families in the province, participated in the Catholic agitation of the late eighteenth century. Owen, who served as a Volunteer in 1782 and was one of the Roscommon delegates to the Catholic convention in 1793, was also active in this campaign and probably became involved with the United Irishmen. However, except for his remark to Wolfe Tone in January 1793 that he was prepared for extreme measures, he steered clear of revolutionary activity, unlike his radical cousin Thomas (of Mount Allen), who in 1801 emigrated to New York; it was there that his son Charles (1804-84) became a prominent Democrat lawyer.
Denis O’Conor’s fourth cousin Dominick O’Conor (d. 1795) had left Clonalis to his wife (d. 1814) and then to Owen as future head of the family. This was disputed by Dominick’s younger brother Alexander, who succeeded him as the O’Conor Don and had delusions of establishing himself as a self-styled monarch in a rebuilt Ballintubber Castle; he and his next brother Thomas, who predeceased him, were described by Skeffington Gibbon as ‘men of high and noble birth, but from their eccentric, secluded, pecuniary difficulties and habits, hardly known beyond the walls of the smoky and despicable hovels in which they lived and died’. After protracted litigation that reduced the value of the property, O’Conor purchased Clonalis outright in 1805, and on Alexander’s death in December 1820 he inherited the headship of the Don part of the old Catholic clan of the O’Conors. The following month he wrote a letter to the press to dismiss rival claims to this title, which the king, however, refused to recognize as an official designation through the issuing of supporters to his armorial bearings.
By the early 1820s the O’Conor Don was one of the most influential of the older generation of reformers in the Catholic Association. For instance, in early 1821 his attendance in Dublin was considered by O’Connell as essential for ensuring Catholic unity on the divisive issue of the proposed royal veto on episcopal appointments, and later that year it was largely at his insistence that the Catholics’ national address to George IV on his visit to Ireland was confined solely to uncontentious expressions of loyalty.
The O’Conor Don, who spoke against the introduction of poor laws to Ireland and the increased Irish stamp and spirit duties at county meetings, 30 Mar. and 12 June 1830, agreed to offer at the general election that summer, when he pledged to support a range of radical reforms and to devote the rest of his life to the Irish cause. Nothing in the end came of a threatened Tory opposition and, benefiting from the able assistance of his sons Denis and Edward as agents, he was returned unopposed as the first Catholic to represent Roscommon since his ancestor Sir Hugh.
According to the letters that the O’Conor Don sent home from London, he apparently threw himself into its parliamentary and social life and complained so much of weariness that his family feared for his health.
The death of my most respected and loved friend, your father, was to me a severe blow ... How little does the world know of the value of the public services of men who like him held themselves always in readiness without ostentation or parade but with firmness and sincerity to aid in the struggles which nations make for liberty ... I really know no one individual to whom the Catholics of Ireland are so powerfully indebted for the successful result of their contest for emancipation ... His was not holiday patriotism ... No, in the worst of times and when the storms of calumny and persecution from our enemies and apathy and treachery from our friends raged at their height he was always found at his post.O’Connell Corresp. iv. 1821.
