King joined the Newtownshandrum club at a young age and played in all grades at juvenile and underage levels. On 19 October 1997, he was just 15-years-old when he lined out at left corner-forward when Newtownshandrum faced St. Finbarr's in the Premier County Minor Championship final. King was held scoreless in Newtown's 2-13 to 0-10 defeat. King subsequently progressed onto the Newtownshandrum under-21 team. On 29 November 1998, he was at left corner-forward when Newtownshandrum faced Na Piarsaigh in the Cork Under-21 Championship final. King top scored with 1-02 from play in the 1-11 to 0-14 draw. The replay took place on 6 December 1998, with King switching to right corner-forward and scoring four points from play in the 1-12 to 0-07 victory and a first title for Newtown in 25 years. On 12 December 1999, King was at left wing-forward when Newtownshandrum lined out against Erin's Own in a second successive Cork Under-21 Championship final. He scored two points from play and collected a second successive winners' medal after the 1-13 to 1-07 victory. O'Connor lined out in a third successive under-21 final with Newtownshandrum on 17 December2000 when the club faced Glen Rovers. He scored 0-04 from midfield in the 1-17 to 1-07 victory and collected a third successive winners' medal.
Senior
On 8 October 2000, King was selected at right wing-forward when Newtownshandrum faced Erin's Own in the Cork Senior Championship final. He was held scoreless throughout the game but claimed a winners' medal following the 0-14 to 0-11 victory and a first-ever championship title for Newtown. On 15 September 2002, King was at left corner-forward when Newtownshandrum faced reigning champions Blackrock in the Cork Senior Championship final. He was again held scoreless throughout the 1-14 to 0-12 defeat. Newtownshandrum faced Blackrock in a second successive Cork Senior Championship final on 12 October2003 with King lining out at centre-forward. He scored two points from right corner-forward in the 0-17 to 1-09 victory. On 30 November, King won a Munster Club Championship medal after scoring four points from right wing-forward in the 2-18 to 2-09 defeat of Patrickswell in the final. King was at left wing-forward when Newtownshandrum defeated Dunloy by 0-17 to 1-06 in the All-Ireland final on 17 March 2004. On 16 October 2005, King won a third Cork Senior Championship medal when he scored two points from full-forward in a 0-15 to 0-09 defeat of Cloyne in the final. He again scored two points from play when Newtownshandrum defeated Ballygunner to win a second Munster Club Championship title on 4 December 2005. King was switched to midfield for the All-Ireland final on 17 March 2006 but was held scoreless in the 2-08 to 1-06 defeat by Portumna. King lined out at full-forward in a fifth Cork Senior Championship final on 14 October 2007. He was held scoreless throughout the game and ended on the losing side after a 1-11 to 1-07 defeat by reigning champions Erin's Own. On 11 October2009, King was selected on the substitutes' bench when Newtownshandrum faced Sarsfields in the Cork Senior Championship final. He was introduced as a 38th-minute substitute and claimed a fourth winners' medal after scoring a point in the 3-22 to 1-12 defeat. On 29 November 2009, King was again introduced as a substitute when Newtownshandrum won their third Munster Club Championship after a 2-11 to 2-09 defeat of Ballygunner.
Cork
Senior
King was added to the Cork senior hurling team following Newtownshandrum's All-Ireland Club Championship success in 2004. On 27 June 2004, he was an unused substitute when Cork suffered a 3-16 to 1-21 defeat by Waterford in the Munster final. On 15 August 2004, King made his championship debut when he came on as a 61st-minute substitute for Joe Deane at right corner-forward in a 1-27 to 0-12 defeat of Wexford in the All-Ireland semi-final. On 12 September 2004, he was an unused substitute when Cork defeated Kilkenny by 0-17 to 0-09 in the All-Ireland final
Career statistics
Inter-county
Honours
;Newtownshandrum
All-Ireland Senior Club Hurling Championship : 2004
Munster Senior Club Hurling Championship : 2003, 2005, 2009