The country’s Director-General of Health Dr Ashley Bloomfield confirmed the man, 24, had not yet been vaccinated and travels to work in a private car with a colleague.
The man had a sore throat four days ago and tested positive on Tuesday.
The guard had been working at the Grand Millennium hotel in Auckland.
The hotel is a managed isolation facility.
The man was not vaccinated, but would have been offered the vaccine by now.
Investigations are ongoing if the man rejected the offer.
One close contact, his carpooling colleague, has tested negative and is fully vaccinated.
Across New Zealand’s quarantine workforce health authorities are now shifting unvaccinated workers into different roles.
Other close contacts at the Grand Millennium are being investigated.
In addition to the new local case, New Zealand has also reported 23 new positive cases in overseas travellers currently in managed isolation.
Dr Bloomfield said there are currently 95 active cases in New Zealand.
The dramatic uptick in infected travellers comes as countries around the world report growing spikes in new cases.
New Zealand is concerned about the number of travellers from India who are becoming infected with COVID-19 during their journey from India to New Zealand.
Of the 24 new cases reported by New Zealand, 17 are people who have travelled from India.
Health authorities are questioning if the travellers are being infected on their journey because they are testing positive on day zero of testing once in New Zealand.
NSW Premier Gladys Berejiklian said she was unfazed by the single new local case in New Zealand.
“There will be cases pop up unexpectedly but just as I would expect people to keep borders open to New South Wales if we had an outbreak we thought we could manage, I would extend that courtesy to New Zealand as we did to Queensland and other states,” Ms Berejiklian said.
“I don’t worry about outbreaks which can be managed.
“We should expect that during a pandemic.”