Harrington and Romero finished the nine-hole contest at 4-under-par 23 as did Tiger Woods, who used an ace on the ninth hole for his share of the lead.
Woods was occupied receiving an award by the time the playoff came around, leaving Harrington and Romero to battle for the title.
Harrington won the third playoff hole to finish on top at the Par-3 Contest for the second straight year. In 2003, Harrington was joined by David Toms in the lead and the duo shared the title as inclement weather prevented a playoff.
Woods came close to being the one to test history this week since no player who won the Par-3 Contest on Wednesday has ever gone on to win the Masters in the same year.
Instead, Harrington will have the task of attempting to break that trend.
Defending champion Mike Weir delighted the crowd on hand with an ace on the 70-yard second hole.
Jack Nicklaus had some fun in the Par-3 Contest on Wednesday. The six-time Masters champion almost closed the day with a bang when his tee shot to the ninth spun back and missed the hole by a few inches.
'The golf course is in absolutely beautiful condition,' said Nicklaus. 'The fairways and greens are excellent.'
While Nicklaus applauded the condition of the course, he cautioned that the changes made two years ago at Augusta National will be noticed this time around.
'What's changed for the golf course, it's probably what Hootie (Johnson) wanted to have happen here, and that's have the golf course play relatively the same based on equipment,' he said. 'You have to drive the ball straight, and they really put a premium on driving the ball in play and in position to be able to play. If you put the ball on the edge of this rough with hard greens, it's pretty difficult to stop it on those greens.'