Chris Hipkins says he will isolate and try to campaign online after testing positive for the virus on Sunday.
Hipkins, who took over the leadership of the ruling Labour Party from Jacinda Ardern in January, has been struggling to connect with voters in his campaign for re-election.
On Sunday, he took to Facebook to announce he had got the coronavirus after developing cold and flu symptoms on Saturday.
He said he would take his campaign online instead.
“Bugger! After a rough night I woke up this morning feeling pretty unwell and just got this test result,” he said in the post on his official page, sharing a photograph of his rapid antigen test.
“I’m in close contact with New Zealanders on the campaign trail and I don’t want to pass it on to anyone, so I’ll be following the guidance and isolating for a few days or until I get a negative test.”
Hipkins said he would try to continue with as many of his campaign events online as he could.
“There’s a lot at stake this election, and I’ll be working doubly hard when I can get back out there to make sure Labour is re-elected,” he added.
Opinion polls show Labour’s support lagging with the centre-right National Party of former businessman Christopher Luxon on track to form a coalition government with smaller parties.
Hipkins’s COVID-19 test came as his party launched its manifesto showcasing policies, including maths and literacy catch-up courses for schoolchildren who lost study hours because of coronavirus disruption, free dental care for those below 30, more front-line police and four weeks paid parental leave for partners.
New Zealand removed its last COVID-19 restrictions in August, but health authorities still recommend that people stay home for five days if unwell, or if they have tested positive.
That means Hipkins is also likely to miss his next debate with Luxon, which is scheduled for Tuesday night.