After a one-hour delay due to a lightning storm on Thursday, Pittayarat reeled off four birdies in the front nine and another five on the stretch to set the pace on nine-under par in Singapore.
The 21-year-old from Thailand capped off an impressive round in style when he holed a 20-foot putt at the 18th, to ensure four players had to settle for a share of second place heading into the second round.
Scott Jamieson, David Lipsky, Kim Byeong-Jun and Quincy Quek all shot 64s, but it was Pittayarat who is out in front and admitted to being surprised with his blistering start.
He told the European Tour website: "I am very happy with how I played today. I didn't see it coming but it did come.
"I'm feeling good about my game right now. I was just trying to hit straight out there. I managed to hole a lot of putts and a lot of them were unexpected."
In the final tournament of the three-week Asia swing, defending champion Brett Rumford is seven shots off the lead after the Australian came home in 70.
And Alexander Levy, winner of the China Open last Sunday, has ground to catch up as he also on two under.
Jamieson is well poised a shot off the lead and the 30-year-old Scot was understandably encouraged by his start to the tournament.
"I've been hitting the ball well the last couple of weeks, so it was nice to get a round where it all came together," he added.
"There was just the one mistake with the three-putt on 16, but it was pretty far away and pace putting is always difficult in Asia with the grain. It's not what someone from Scotland is used to."