O'Connell was selected for his third Lions tour on 30 April 2013, named in the squad for the 2013 British & Irish Lions tour to Australia. He captained the side in their opening tour fixture against the Barbarians on 1 June 2013 in the absence of the injured Sam Warburton, scoring a try in the 59–8 win. O'Connell came off the bench in the 12–22 win against the Reds on 8 June 2013. O'Connell started against Waratahs on 15 June 2013. He started in the Lions first Test 21–23 victory against Australia on 22 June 2013. O'Connell was ruled out of the remainder of the 2013 tour after suffering a fractured arm in the first Test against Australia. It was announced on 26 June 2013 that O'Connell would be staying on for the remainder of tour in a coaching role.