Kerr, who entered the final round with a one-shot lead over defending champion Feng Shanshan, finished at 15-under after carding a back-and-forth even-par 71.
Although the American managed three birdies on her route to the final hole, bogeys on the 15th and 17th, as well as a double bogey on the par-3 7th put victory in doubt.
Kerr looked to be heading to a four-way playoff with Feng -- who also carded a round of 71 -- and fellow Americans Kang and Concolino as she arrived on the 18th, with all players sharing the lead at 14-under.
Unlike the two leaders, neither Concolino or Kang were troubled by the challenging conditions as they shot impressive rounds of 67 and 66 respectively to give themselves a chance of snatching victory in Kuala Lumpur.
That wasn't to be as the 40-year-old held her nerve to sink a final-hole birdie to finish 15-under and seal her first win of the year.
"It was meant to be," Kerr said after the dramatic finale. "What a way to win. I always said I wanted to get a win in my 40's and I got it pretty quick."
"To do what I do for a living is amazing," she continued "This tournament is a beacon for women's health and raising awareness for breast cancer is near and dear to my heart. I'm so proud to be the champion of this tournament."
Elsewhere, Canada's Brooke Henderson played the round of the day as she carded a 7-under 64 to finish fourth at 13-under.