The win was Mamat's first on the European Tour. He claimed the Royal Challenge Indian Open in March of 2004 on the Asian Tour, which co-sanctioned the event along with the European Tour.
Mamat also became the first Singaporean to title on the European Tour.
Dougherty birdied the 72nd hole to put pressure on Mamat, but ultimately came up short. He also shot a 1-under 71 on Sunday to post an 11-under-par 277 at the Masters Course at Laguna Golf and Country Club.
Malaysian Open champion Charlie Wi and Ross Fisher began the final round tied for third place and that's where they finished. Each shot a 71 and tied at minus-10.
Mamat began the final round with a one-shot lead, but extended to two with a birdie at the first. He added another birdie at No. 2 and was three ahead of Dougherty, who would fall on some seriously hard times on the front nine.
The defending champion bogeyed the fifth, sixth and eighth holes to fall down the leaderboard. Mamat continued to make pars and after Fisher bogeyed the sixth, Mamat found himself four clear.
That margin did not last long as Mamat also bogeyed No. 6. He dropped another shot at the eighth and was only two ahead, this time over Wi. Mamat was 11- under par and used par as his ally. He parred holes nine through 14, then birdied the 15th. Wi birdied the same hole to remain two back, but last year's winner made a move.
Dougherty birdied the 11th, 15th and 16th holes to creep up to 10 under par, two behind Mamat and tied with Wi. Problems arose for Wi at the 17th that led to bogey, essentially knocking him out of the tournament.
Both Mamat and Dougherty parred the 17th and Dougherty made things interesting with a birdie at the last. Mamat ended the drama with a par of his own, earning him a wire-to-wire victory.
Dougherty appeared to be out of the tournament with his dreadful play on the opening nine, but the rebound came up just short.
'I have been threatening to play that bad all week and it just all went horribly wrong for me on the front nine,' acknowledged Dougherty, who could have become the first player in tournament history to successfully defend. 'I fought back well, but it was not enough in the end. Mardan finished off very well.'
Chapchai Nirat shot a 1-under 71 on Sunday and tied for fifth place with Jonathan Lomas, who carded a 6-under 66 in the final round. The pair finished at 9-under-par 279.
Jyoti Randhawa (68) and Andrew Butterfield (72) shared seventh place at minus- 7. Marcus Fraser (71), Marcus Both (69), Anders Hansen (73) and Prayad Marksaeng (72) tied for ninth at 6-under-par 282.