Waiheke Island's Countdown is banning plastic bags, and locals are hoping other supermarkets around New Zealand will follow.
Residents have been lobbying for years to get retailers to stop using single-use bags because of the threat they pose to the local marine life.
It means people will have to bring their own bag, buy a re-usable one or carry their shopping unbagged.
Waiheke Local Board chair Paul Walden said other supermarkets might be reluctant to drop plastic bags because of their competitors.
"It sort of leaves them a little bit vulnerable unless it's regulated nationally. But when you're on an island, and there's one supermarket here, it does create that opportunity.
"And who knows? Maybe it will be just another example of a philosophy change that can roll around the country."
Countdown corporate affairs manager James Walker said feedback so far on the island had been nearly all positive.
The move would also cut some costs, he said.
"Single-use plastic bags come at a cost to any retailer, so if we're not giving them out, that is a cost saving for us."
The company would keep a close watch on how the bag-free store went but there were no firm plans to roll it out anywhere else, he said.