Winner of a playoff at Carnoustie in 2007 and a second title at Royal Birkdale by four shots last year, the 37-year-old Irishman was never in contention this time around. His error-ridden third round underlined his poor form coming into the championship.
Harrington missed five cuts on the European and PGA tours, although he won a low-key tournament in Ireland before heading for Turnberry.
I was just poor today and made the wrong decisions. On a windy, tough course you need things to be going with you, to be feeling like youre on top of the course. I was a little bit behind the eight ball and Ive not made things happen.
Harrington, who also won last years PGA Championship, went into the third round eight shots off the lead but convinced that his game was in good shape and that all he needed was for a few putts to drop in.
When he rolled in a 10-footer at the first, his evaluation seemed right and hopes rose of a charge up the leaderboard.
But he missed another 10-foot birdie putt at the second and then picked up his first bogey by three-putting the third. His round went downhill from there.
Two 6s in a row ' a bogey and a double bogey ' meant he dropped more shots by the turn, and three more bogeys on the back nine effectively ruined his championship chances as he finished the third round to stand 9-over 219.
I hit an ugly putt on the second and that missed and then three-putted the third, he said. Poor error on six and again on seven, couple of good shots wasted there. On the back nine I kept leaving putts. I actually got three putts up to the hole all day and three-putted all of them. It wasnt my day.
At least Harrington can now look ahead to his defense of the PGA Championship at Hazeltine Aug. 10-16.
Im looking forward to a couple of weeks off and do a bit more work and Ill look forward to getting back and building up for the PGA, Harrington said.