Cotton On has committed to the 1700-square-metre level six of the 11-level office building, dubbed Tower One, which is now fully leased. Fellow tenants include The Body Shop, Shaver Shop, Ricegrowers (SunRice), Victory Corporate Serviced Offices and Sigma Pharmaceuticals.

Colliers International director Rob Joyes, who leased the speculatively built 16,000-square-metre tower with Travis Myerscough and Kevin Tutty, said retailers had been targeted for the space.

Other retail companies, JB Hi-Fi and Boost Juice's parent company, Retail Zoo, are located in a separate four-level 6000-square-metre office building completed in 2008. Cotton On Group's global head office is on a sprawling campus in North Geelong.

"Retailers jumped at the chance to position their offices close to some of their best performing stores," Mr Joyes said.

"It was fully leased nine months ahead of schedule and the leasing team continues to receive inquiries from people who want to know when the next building is coming," he said.

The building has achieved net rents ranging from $350-$360 a square metre, he said.

Colliers International has moved from Mulgrave to take space in the tower and Chadstone owners, the Gandel Group and Vicinity Centres, also have offices in the building.

The distinctive dark glass tower sits within the 27.5ha Chadstone Shopping Centre footprint in Melbourne's south east suburbs. The $5 billion centre, the largest in Australia, is undergoing its 40th revamp in nearly 25 years and now tips the scales at 212,300 square metres and 10,000 car parks.

In October, stage one of a $660 million new 46,000-square-metre wing was unveiled, boasting two-level stores for Uniqlo, H&M and Sephora, a restaurant terrace and a 13-screen Hoyts multiplex.

Stage two, featuring the Legoland Discovery Centre and international luxury retailers Valentino, Celine and Loewe, is set to open mid-year.

A Vicinity spokesperson said work on a future masterplan is underway with a proposed hotel under consideration. A podium for the hotel has already been constructed next to Tower One.