Currently the shop's fit-out is shrouded in secrecy from the street front, but the space it'll occupy is 1200 square metres in size and covers two floors.
A complete refit and seismic strengthening is taking place, as the building was first built in the late 1970s.
Showroom 22 director Murray Bevan said it's expected the store will open by November 3.
"Topshop Topman Wellington is currently on track to open on Thursday 3rd November 2016, and we are now in the planning stages for the opening events."
Meanwhile, its Christchurch store is expected to open in early 2017.
Prior to H&M and Zara's announcements, Topshop was the first international fast fashion brand to enter the New Zealand market and stir up interest.
Its Auckland store opened in March last year to much fanfare, with a queue of customers snaking all the way down Wyndham St well before its opening.
Vouchers of up to $500 in value for the first 300 people in line spurred hype arounding the opening, while security guards were put in place to control the crowds.
Personal stylists, live DJs and an in-store nail bar were also on hand for the launch.
As for other international names descending on Wellington, most in the industry regard Zara and H&M as almost a definite for opening up stores in the capital.
H&M has already announced two stores in Sylvia Park and Auckland CBD's downtown shopping centre, while Zara has confirmed it'll open a store at Sylvia Park.
At a Wellington Our CBD meeting held in January, attendees were told Zara and H&M representatives were scoping the local area heavily.
However, concerns were raised about finding sites big enough to accommodate the retailers.