Aucklanders spent $1.3 billion on online shopping last year, putting New Zealand's largest city at the top of the list for total online retail spend.
The Canterbury region spent $427 million on online shopping last year and Wellington spent $409m, a report commissioned by NZ Post reveals.
New Zealand combined spent a total of $3.6b on online purchases last year - the equivalent of 8.1 per cent of all retail sales or $746 for every resident.
Gisborne spent more money online than in physical shops last year, and the biggest growth in the number of online transactions came from Northland.
In rural New Zealand, online shopping is growing at a rate of 15 per cent.
Online shopping in New Zealand grew 13 per cent year on year compared with just 1 per cent for bricks and mortar, fuelled by a 23 per cent increase in spending at overseas websites and 9 per cent increase at local sites.
NZ Post chief marketing officer Bryan Dobson said the global e-commerce market was double the size it was five years ago - and growing.
"Online sales are growing ten times faster than offline sales," Dobson said. "By 2021 it is projected 17.5 per cent of all global retail spend will come from eCommerce."
The report found e-commerce was growing the fastest in the regions.
"In the regions, it's around the availability of and access to products. In Auckland and the metropolitan areas it's more driven by convenience and people needing to optimise their time a little bit better," he said.
"The most dominant category for online shopping in New Zealand goes to this big catch-all called department and variety; the likes of The Warehouse or Farmers, organisations who have made a successful transition to e-commerce.
"Interestingly, in terms of spend, food is the second largest category and it's one of the fastest-growing."
More Kiwis are shopping online than ever before, with women opting to shop on the web more frequently than men.
"Initial analysis showed that men and women, the proportions of who shop online, are very similar but when you get underneath that behaviour it's quite different," he said.
"Women who shop online shop more frequently and spend smaller amounts, men shop a little bit less but spend more and as a result women contribute more to transactions but men make up a larger proportion of the actual dollar value spend."
NZ Post processed 70 million parcels last year and experienced more than 100 per cent growth in the number of parcels shipped between China and New Zealand.
It has delivered 39 million parcels in the first-half of the current financial year, up 9.9 per cent from the same period a year earlier.
Dobson said NZ Post expected to see continued growth in online shopping.
"Volumes really start amping up from November towards Christmas, but what's really interesting is they don't go back down to the old levels in the New Year. Each year they increase, and we're expecting that trend to happen again this year."