Foodstuffs supermarkets Pak'nSave and New World have confirmed they will turn away any customers without face masks during the COVID-19 lockdown, while Countdown will provide face coverings to customers without.
From Thursday, face masks are compulsory for all supermarket staff and customers while at alert level four.
Foodstuffs' South Island chief executive Steve Anderson told RNZ they have a 'no mask, no entry' policy.
"It will be a challenge. But look, the vast majority of New Zealanders get it and realise that it's important for everybody to behave themselves.
"There are going to be some people who are upset about it.
"We've just got to manage this really well and we're really well practised at managing it from the previous lockdown."
He said it's up to individual shop owners if they want to provide masks at the front door.
Face masks are also a condition of entry at Countdown supermarkets around New Zealand, but shops will be providing them for any customer who doesn't have one.
"We are following the advice of the NZ Police that if customers become aggressive, our team members should not enforce this as it becomes too dangerous for them," a spokesperson said.
"We strongly hope that our team are not put in this position and that New Zealander will do the right thing and wear a mask."
The spokesperson said Countdown has been advocating for the Government to make masks mandatory so they are "very pleased" to see them take that action.
Prime Minister Jacinda Ardern announced the mask mandate for supermarkets and other essential services, like petrol stations, on Wednesday.
"From 11.50pm tonight, it will be mandatory for everyone aged 12 and over to wear a mask when they are visiting any of the essential services that are currently open, including supermarkets, pharmacies and service stations," she said.
Mandatory mask use includes places like bus terminals and taxis.