[1] O'Connor was born at Cradock and educated at Christian Brothers' College, but was raised at Hawker, where he was the son of the local storekeeper.

In 1909, he disposed of the Lameroo store to Eudunda Farmers Ltd and went into partnership as an auctioneer and land agent in the firm of McNamara and O'Connor until 1912.

By 1914, he was reported as living in Adelaide and working as a land agent there, though he retained ownership of farms in the district and continued to be involved in local causes.

[29][2] In December 1920, he announced that he would not contest the 1921 election as a Liberal and had not decided whether he would stand at all, advocating that the non-Labor parties put their differences aside and form a united front; he reaffirmed that he continued to support government policy.

[35] He appealed the result in the Court of Disputed Returns, alleging irregularities in the conduct of the election, but withdrew the petition three months later before it had been heard.

[41] In June 1926, following his prominent role in the Senate campaign, he announced that he would reject overtures to run at the next election, retire from politics and would join the firm of Coles Brothers Ltd., managing their real estate branch, later forming his own short-lived partnership of O'Connor, Alexander and Flecker in 1931–32, which ended acrimoniously amid legal action.