The Team BRM/88 Racing driver scored a free kick even before the race started thanks to delays for James Golding and Roberto Merhi.
The Garry Rogers Motorsport pair had qualified second and third, just 0.05s and 0.14s respectively behind Mawson, but were forced to start from the lane after not making it out to the grid.
That left Mawson alone on the front row, GRM's Aaron Cameron left as his closest rival starting out of fourth.
Mawson made full use of the clear air at the start, quickly establishing a two-second gap over Cameron and the chasing pack.
He then steadily worked that gap out to 6.2s over the 26-lap journey as he cruised to victory.
"It's a perfect start to the season," said the two-time consecutive Gold Star winner. "The car was mega. We're looking good at the moment."
Behind Mawson there was tense battle for second and Cameron came under increasing pressure from third-place Cooper Webster.
Ultimately Cameron was able to do enough to hold on to second, before revealing post-race that he had no radio – and no idea of the lap count.
"It was a bit of a rush to get ready for that race," said Cameron, who is on double duty in S5000 and TCR Australia this weekend.
"I didn't have radio, so I didn't know what the heck was going on. I didn't even know how many laps the race was.
"So I just stayed there. Joey was a bit quicker so I just tried to mind my own business, but Cooper just wouldn't go away."
Jordan Boys finished fourth after holding off a recovering Golding, who was just a tenth back by the finish.
Merhi, meanwhile, worked his way to sixth on the road, but was dumped to ninth in the final standings due to a 10-second penalty for passing a red light at the end of pitlane.
That promoted Blake Purdie to sixth ahead of Nic Carroll and Zane Goddard.
The S5000 action continues with two more races tomorrow at 11:45am and 2:20pm local time.
