Queues stretched outside Westfield shopping centres from 7am on Wednesday and thousands more are expected throughout the day.
With Boxing Day sales underway across the country, Westfield New Zealand regional manager Paul Gardner says there's no sign of it slowing down.
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"Each boxing day has surpassed the previous one," he told Newshub.
"I think what generally happens is [customers] research online, and if anything, the research which is possible online was creating more urgency."
But Mr Gardner said the malls are well-equipped for large numbers.
"There are a large number of car park attendants to make sure that the experience from arrival is as good as possible.
"We've got ambassadors on the floor; we've got staff to make sure that everybody is as safe as they could possibly be."
Auckland's Sylvia Park is also bursting with shoppers and queues for the nearest motorway exit have built up significantly in both directions.
"Traffic continues to be heavy in both directions through the Mt Wellington interchange with queues at both the northbound and southbound off-ramps," the NZTA said on Twitter.
"Avoid the area and continue to expect delays."