Bhullar, the only Indian to make the cut, scored six birdies against two bogeys, both of which came on the back nine on 14th and 17th holes.
Harding made three early birdies to share the lead but his chance looked to have gone as he made two bogeys and South Korea's Jinho Choi signed for a brilliant 64 to set the clubhouse target at 11-under.
Birdies on the tenth and 12th put him back in contention and further gains on the 15th, 17th and 18th handed him a two shot lead at 13-under after a 66.
He faced a nervous wait as the final groups finished up but nobody could catch him, with countrymen Christiaan Bezuidenhout, George Coetzee and Erik van Rooyen, Spaniards Jorge Campillo and Nacho Elvira, Swede Anton Karlsson, Frenchman Mike Lorenzo-Vera, England's Oliver Wilson and Choi in a European Tour record nine way tie for second.
The victory is a fifth in nine months and four different countries worldwide for the 33-year-old Harding after he claimed back-to-back Sunshine Tour wins in May and repeated the feat on the Asian Tour in July.
"It feels good," said Harding, who had two top fives and three further top 20s from eight events coming into this week.
"It was nerve wracking, especially coming off, it's a situation I haven't really been in. I didn't enjoy it but it's good fun, I'm glad it happened and now we move on.
"I get into the events that I'd like to be into again, the schedules change, I'm no longer having to pick and choose. I'm looking forward to seeing what happens going forward and playing in some bigger events.
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