The 26-year-old took out the 85kg snatch at the competition in Port Moresby, one of the first qualifying events for the 2016 Rio Games.
Chamoun, who was diagnosed with the degenerative condition retinitis pigmentosa at age seven, also took out silver in the clean and jerk and overall.
"The crowd was buzzing, so much energy," he told Olympics.com.au.
"My snatch was awesome, to get the 139kg was huge."
The Sydneysider competed at the Commonwealth Games in Glasgow last year, where he failed to complete one lift.
"These are the best medals I've ever had. It's my best international total," he said.
Chamoun said having his father George there as his coach made all the difference.
"I couldn't do it without him. It's not only coaching me, it's full time with me because of my condition," he said.
"Dad was a weightlifter and now my sister also competes - we're a close family."
His younger sister Sabah scored gold earlier in the Games in the Oceania Youth event.
