Harrington made his first start of the 2012 PGA Tour season at the AT&T Pebble Beach National Pro-Am where he finished joint top of the Pro-Am leaderboard, alongside partner J.P. McManus, with Brian Harman and Greg Ontiveros. Harrington also enjoyed a good finish in the overall tournament with a tied for seventh finish. In March 2012, Harrington shot a 61 in the first round of the Transitions Championship to set a new course record at the Copperhead Course. This was also Harrington's lowest ever round on the PGA Tour. He could not maintain his brilliant first day's play over the remaining three rounds though and finished in a tie for 20th place.