The fashion retailer has secured 61,000 sq ft of space over five floors of the Wells & More building on Mortimer Street and Wells Street in central London.
The new office building will house 250 staff relocated from both its Weymouth office and its existing London office near its flagship store in Marble Arch.
The retailer agreed the deal with Great Portland Estates on Friday.
The signing follows the retailer’s decision to relocate its marketing, buying and design teams from Weymouth as revealed by Retail Week, to enable it to compete on an international scale with its competitors.
Chief executive Carl McPhail told Retail Week that the move to the contemporary building in London’s West End will help to attract people of the highest calibre to spearhead its global plans.
The retailer is still in consultation with staff over the office relocation but expects to begin the transfer to Wells & More in June.
McPhail declined to comment on how many staff in Weymouth have expressed an interest in moving with the retailer to London.