Westpac and financial services firm KPMG will be the main tenants at the controversial Barangaroo development on Sydney Harbour.
Westpac had committed to a long-term lease that will make it an anchor tenant of the $6 billion office, residential and parkland development, the bank said on Friday.
Westpac will move in from 2015, and take 60,000 square metres of office space.
The bank's current head office in Sydney will remain, but two other smaller sites in the city's CBD have been bought by Lend Lease, the developer of Barangaroo.
"Westpac's anchor tenancy in this important development ... demonstrates our commitment and confidence in the future of Sydney as a financial centre," Westpac chief executive Gail Kelly said in a statement.
KPMG has also signed a lease agreement with Lend Lease, although the details are yet to be made public.
Construction of the Barangaroo development, located on the western edge of Sydney's CBD, began in 2011, despite opposition from some local residents and businesses who wanted the area to remain in public ownership.
Concerns were also raised about architectural compatibility and environmental issues, including pollution.