The 29-year-old from Johannesburg, trailing by four at the halfway stage, hit eight birdies and an eagle to be 18-under 198 and move ahead of 36-hole joint-leader Liang Wenchong of China, who shot a 69 for outright second.
Thailand's big-hitting Kiradech Aphibarnrat (66) and Scotland's David Drysdale (68) were tied third, a further shot behind on 14-under.
Aiken started with a birdie on the first and a eagle on the second and never looked back from there.
"I concentrated very hard to play one shot at a time and it seemed to work," Aiken told the European Tour website (www.europeantour.com).
"I got off to a great start... holing a pitch shot on the second for eagle always helps.. and from then on I just stuck to my game plan. All in all I'm very pleased with the way I played."
Some scintillating iron play ensured that the South African, who briefly shared the lead with Kiradech, could set up more birdie opportunities.
"I've been playing very well the last four months and just haven't converted opportunities," said the world number 129, chasing a second European Tour win after his maiden victory in 2011.
"Fortunately this week I've converted a lot of the opportunities that I've had. The majority of them have gone in from inside ten feet and that's what makes the difference from a scoring point of view."
Former Asia number one Liang's round was spoiled by two bogeys when he missed a couple of short putts but he did not lose hope.
"The key is to stay patient," Liang said. "I'm just three shots back and I'm confident that the gap can be closed.
"Anything can happen in golf and I only need to believe that I can do it. Hopefully luck will play a part as well."
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- Kiradech Aphibarnrat