Countdown's plan to phase out plastic carrier bags takes effect this month, when 10 stores leading the charge from May 21.
The initial batch of stores will provide customer feedback, which will inform the rollout across all Countdown's 182 supermarkets before the end of the year.
Countdown's general manager corporate affairs Kiri Hannifin, said getting rid of 350 million plastic bags a year was the right thing to do.
"We've all seen the pictures of our environment and marine life suffering because of plastic pollution, and the impact on our ecosystems is unacceptable," Hannifin said.
"These 10 supermarkets are just the start, but they're of huge importance to test what's been in planning over the past months.