In a post-Cabinet media briefing Monday afternoon, Ardern announced Cabinet had made the decision to allow Recognised Seasonal Employer (RSE) workers from those countries to travel one way, without using MIQ.
The countries this would apply to reflected the fact all three nations had experienced very few cases of Covid-19, she said. Tonga had seen zero Covid-91 cases, Samoa just one, and Vanuatu had four - all those cases having been at the border with no community transmission.
"We know our agricultural sector is experiencing challenges," she said. "We've heard the call from Primary sectors and others to bring in additional workers in a safe way and we think that is now possible.
"We'll be working through some of the detail including repatriation ... so that we don't risk stranded workers."
The government is also looking at additional health precautions for the workers.
She said 150 workers were being brought in every 16 days but this would open up for significantly more.
The government did not know the exact number of additional RSE workers expected to come in, but Ardern there were about 7000 in New Zealand right now and the norm was about 10,000. One of the constraints is the one-way nature of the restriction-free travel, she added.
"Travellers would still undergo quarantine on return to their home country, as has been their home country's policy."
Immigration Minister Kris Faafoi told the media gathering he had been speaking to the industry, and businesses were keen to work with the government on ensuring there are enough workers to meet the demands of the horticulture sector.
The government in May announced an expansion of Recognised Seasonal Employer (RSE) and other seasonal workers into New Zealand, and in June announced an automatic six-month extension to Working Holiday and Supplementary Seasonal Employment visas, and expanded its categories to all industries.
However, industries have remained concerned at what they said was a continued lack of staff, with the hospitality industry in particular frustrated over visa settings, exacerbated by the resumption of restrictions for travel from Australia.
Unions have claimed the hospitality shortage is due to low wages or lack of a viable careers in the industry rather than lack of labour.
In April, a report found the RSE scheme was not a benefit to the wider economy.
Photo file New Zealand Prime Minister Jacinda Ardern