Developer Gareth Graham's £70 million (€79.4 million) Merchant Square project in Belfast has become the first to win backing from the Northern Ireland Investment Fund.
Mr Graham's vehicle Oakland has begun work on the development, which will involve refurbishing Oyster House in central Belfast and adding three storeys to the structure.
The Northern Ireland Investment Fund has committed to funding the project, along with Oakland itself and Fairfield.
Merchant Square is the first to secure backing from the Northern Ireland Investment Fund, which agent CBRE administers on behalf of the Stormont government.
The building will hold 227,000sq ft of offices and shops, and house up to 3,000 workers after it is finished in the third quarter of next year.
Oakland's Guy Hollis pointed out that demand for grade-A offices in Belfast was growing.
"Our project will have a multiplier effect around Wellington Place, Queen Street and College Square, " he said.