The prime minister was due to marry long-term partner Clarke Gayford later this month in a ceremony near Gisborne, on the North Island's eastern coast.
However, on Sunday, when announcing New Zealand's first confirmed community spread of the infectious COVID-19 variant, she confirmed the nuptials were off.
"My wedding will not be going ahead ... such is life," she said.
"I am no different to - dare I say it - thousands of other New Zealanders who have had much more devastating impacts felt by the pandemic.
"The most gutting of which is the inability to be with a loved one sometimes when they're gravely ill. That will far, far outstrip any sadness I experience."
As of midnight on Sunday, New Zealand will shift from "orange" to the stricter "red" settings on its traffic light-style system for COVID-19 management.
Red settings require additional mask use in public settings, require hospitality venues to cap indoor patrons at 100 and seat them all, a cap that also applies to events and gatherings.
Ms Ardern's wedding, reportedly set to host around 180 guests, falls foul of those gathering limits.
She could proceed with a smaller event - however to do so would have risked a backlash, and runs contrary to her public health ethos.
"I just joined many other New Zealanders who have had an experience like that as a result of the pandemic," she said.
"To anyone who's caught up in that scenario, I'm so sorry.
"But we are all so resilient. I know we understand that we're doing this for one another and I know that will help us continue on."
Weddings by sitting heads of government are extremely rare: an Australian prime minister has never done so.Â
Ms Ardern and Mr Gayford, a television presenter and celebrity fisherman and DJ, have one daughter, three-year-old Neve.
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