O'Connor first lined out for Kilkenny as a 16-year-old when he was selected for the minor team in advance of the 1981 Leinster Championship. He won his first Leinster Minor Championship medal, albeit as a non-playing substitute, on 12 July 1981 after Kilkenny's 3-10 to 3-09 defeat of Wexford in the final. On 6 September 1981, O'Connor was once again listed amongst the substitutes when Kilkenny faced Galway in the All-Ireland final. He remained on the bench for the entire game but collected a winners' medal after the 1-20 to 3-09 victory.