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.
"Moving away from 350 million plastic bags takes a fair bit of work behind the scenes and by our team in our stores; these first stores will test our thinking, our training and our processes to ultimately help ensure a smooth transition for all of our customers and team when we make the change across the country."
Countdown isn't the only supermarket chain set to phase out plastic bags in New Zealand.
Last year, Foodstuffs also announced that it would move away from plastic bags at checkouts.
Foodstuffs also plans to discontinue plastic bags by the end of the year.
The first 10 Countdown stores:
Dargaville
Aviemore Drive (Highland Park, Auckland)
Roselands (Papakura, Auckland)
Northwest (Massey, Auckland)
Grey Lynn (Richmond Rd, Auckland)
Gisborne
Johnsonville Mall, Wellington
Victoria Ave, Whanganui
Redwoodtown, Blenheim
Ferrymead, Christchurch