Eager shoppers have been queuing since as early as 6pm last night.
Vouchers of up to $500 in value being offered to first 300 in line have spurred the hype surrounding the opening.
Security guards are in place to control the crowd in case the situation gets out of hand.
After the long-awaited opening, the store will feature live DJs over the first two days, plus a social media corner for people to print out their Instagram snaps and an in-store nail bar.
Personal stylists will be on hand to guide people through the cavernous two-storey, 1200-square-metre store, and a complimentary gift will be given to customers who spend over $200.
Topshop has been stocked at Karen Walker's store, The Department Store, in Takapuna since 2009.
However, the offering at The Department Store was nothing compared to the variety on offer at the Queen St premises.
Topshop and Topman on Queen St will receive up to 300 new items a week. Pricing will be similar to what Topshop lovers have been seeing from the UK brand’s home base online.
The New Zealand Topshop and Topman chain is owned and operated by Top Retail.
Top Retail is 50 percent owned by New Zealand clothing chain Barkers and 25 percent owned by Karen Walker and her husband Mikhail Gherman. The remainder is owned by Christchurch rich lister Philip Carter's company, Crossing CBD.
UPDATED: Gabriel Lai, a 20-year-old student, says he was about number 55 or 56 in the queue when he got there just after 6am this morning.
He received a $20 voucher for his efforts and says he was not disappointed with the store.
Keen shopper Gabriel Lai on the white carpet
"I got told students get a 10 percent discount whenever we buy anything, so I'm pretty sure as soon as I get my next paycheck, I'm going to shop until I drop," he says.
He reckons the clothing selection for men is big, but it's obviously much bigger for women, with the ratio being 40 percent mens clothes to 60 percent womens clothes.
He says as soon as the store's doors opened at 10am, people were "swarming".
"People tried to slip in as quick as possible before being stopped by the guards," Lai says.
When Lai spoke to The Register at 2pm, there was still a queue outside the shop.