The 38-year-old nephew of former European Ryder Cup captain Bernard Gallacher looked on in delight as his five-iron from 221 yards sailed straight into the cup on the fourth hole at the Greg Norman-designed Earth course.
The ace completed a spectacular opening to his round because the experienced Scotsman had opened up with a hat-trick of birdies thanks to two putts of eight feet and one of 10.
"I don't remember ever having a start like that before although I had a birdie-birdie-par-eagle run at the Dubai Desert Classic when I had a hole-in-one there in February," Gallacher told Reuters in an interview at the final event of the European Tour season.
"I also had a hole-in-one at that tournament five years ago. I saw the ball go all the way into the cup today," he said after finishing high on the leaderboard with a 12-under tally of 276.
Gallacher's ace at the Emirates Club in February helped him finish runner-up to Spain's Rafael Cabrera-Bello.
"I'm delighted with my season, the only thing missing has been a win," said the Scot. "Hopefully I can get one next year."
Gallacher, who was watched by his young son Jack on Sunday, put off an operation on a torn cartilage in his right knee in order to play in this week's tournament.
He now plans to undergo surgery on Friday and will be out of action until the tour's three-event 'Middle East swing' starts in Abu Dhabi on Jan. 17.
"At the moment I can't even bend down to see the lines on my putts," said Gallacher, who formed a dynamic two-ball with Sergio Garcia in the final round at the Earth course as the Spaniard equalled the course record of 64 for the second time this week.
Former world number two Garcia returned six birdies and an eagle to finish two strokes better than Gallacher on 274.
The Scot claimed the only victory of his career when he won the Dunhill Links Championship in his native country in 2004.
That year saw him finish a career-high 15th on the European money-list.
Gallacher won a Mercedes for his hole-in-one in February's Dubai Classic. His reward for Sunday's ace was a two-night stay in a local five-star hotel.