Ten Countdown supermarkets will go completely plastic bag-free in two weeks' time, marking the first step towards the chain phasing out single-use bags from all its stores.
Customers at the chosen stores will either have to bring their own bags or buy a reusable bag at the checkout.
"Whatever you bring, we'll pack it for you," Countdown spokeswoman Kiri Hannifin told Stuff.
"If you bring a bucket or a wheelbarrow ... then that's cool, and if you forget, then we'll have some options available."
Countdown's decision to phase out bags, announced in October 2017, was welcomed by environmentalists and shoppers.
"Massive props to Countdown today," Greenpeace said in a statement at the time.
They've taken a bold move that makes them leader of the pack on plastic reduction."
New Zealand-based marine conservation group Our Seas Our Future said they hoped the move inspired other retailers.
"We hope that this sets a precedent for other major supermarkets to take corporate responsibility in phasing out single-use plastic bags."
Auckland Mayor Phil Goff said he hoped others would follow suit - and it wasn't long before New World made a similar announcement.
The following Countdown stores will go plastic bag-free on May 21.
- Aviemore Dr, Highland Park, Auckland
- Roselands, Papakura, Auckland
- Northwest, Massey, Auckland
- Johnsonville Mall, Wellington
- Victoria Ave, Whanganui
- Redwoodtown, Blenheim
- Ferrymead, Christchurch
- Grey Lynn, Richmond Rd, Auckland