Cooper Webster took pole for the opening 15-lap race of the weekend, but was jumped by Mawson on the run to turn 1.
The reigning Australian Drivers' Champion then settled into a comfortable lead ahead of Webster and Aaron Cameron.
The lead continued to look comfortable until lap 7 when the safety car was called due to Mark Rosser beaching his car on the outside of turn 1.
The caution last two laps, the race resuming as a time certain affair on lap 9.
Webster mounted a brief challenge at the restart, but when there was no way through he was powerless to stop Mawson charging to a fourth win from the four races so far this season.
"That was a really good race," said Mawson. "The easy plan was to try and get Cooper off the line, which we did. And then really it was managing the tyre and managing the push-to-pass.
"I had to burn up a bit [of push-to-pass] at the restart because Cooper was about to overtake. And then I had about 10 seconds less and I burnt it up open the last lap to try and get the fastest lap.
"I'm happy with that."
Webster, meanwhile, said losing the start was critical to the outcome.
"I'm a little bit disappointed, we did start on pole and I didn't get the best start," he start. "In the second phase I got too much wheel spin.
"On the restart I drained the boost and did my best, but [Joey] defended well and second was the best I could do."
The battle for third was much closer, James Golding executing a last-lap pass at turn 4 to bump Garry Rogers Motorsport teammate Aaron Cameron off the podium.
Golding was, however, still left disappointed he couldn't factor in the battle for the win.
"It's a solid finish," said the Supercars regular. "I was hoping we were going to get a couple more positions in that one.
"With the safety car, I thought we were on there – I'd saved a bit more push to pass than the other boys. But you burn so much up getting around.
"It's difficult, you've got to really think about everything hat's going on and not use too much."
Cameron ended up fourth ahead of Blake Purdie, Nic Carroll and Winston Smith.
The round continues with a second race at 10:20am tomorrow.
