One of the world's biggest real estate firms will move into the World Trade Center.

Cushman & Wakefield signed a 10-year lease on the 45th floor on Sept. 1, Cushman & Wakefield and the Port Authority, which approved the deal, announced Thursday.

The addition of the firm means that the tallest building in the western hemisphere is now 58% leased.

"This transaction with Cushman & Wakefield underscores the diversity of tenants, both domestic and international, who seek office space at One World Trade Center," Port Authority Acting Director of WTC Redevelopment Beth Wolfowitz said in a statement.

Cushman & Wakefield executive vice chairman Tara Stacom said her corporation, which as 250 offices in 60 countries, chose the location for its proximity to a major transit hub and it wanted to be part of the growing downtown financial environment.

"This distinctive property is anchoring Lower Manhattan's rapid transformation from a financial center to an exciting and diversified, 24/7 community," she said in a statement.

Condé Nast, the tower's anchor tenant which leased 1.2 million square feet between the 20th and 44th floors, is scheduled to move into the World Trade Center later this fall.

Other tenants include the federal government, Australian tech company Servcorp, ad agency KiDS Creative, Legends Hospitality, which will operate the observation deck, London based investment firm London-based BMB Group and China Center New York LLC.