O'Brien announced his retirement from inter-county hurling on 26 November 2014. In a released statement he said "I wish to announce my retirement from the Tipperary Hurling team. It has been an honour to have represented my county at senior level since my debut in 2001. I would like to thank everyone who has supported me and made it possible for me to play, most importantly my family and friends, my club Toomevara, the management and backroom teams throughout those years which are too many to mention and also the Tipperary public. I have made many great friends over those years and I would like to wish the current panel and management team the very best of luck."