The Queen's Parade project has been in the pipeline for nearly 15 years. It includes proposals for a hotel, convention centre, homes, offices and entertainment space on a once-bustling terraced promenade left largely derelict - boarded up buildings and gaping holes replacing thriving businesses.
Developer Karl Greenfarm Properties Limited agreed to sell the land portfolio to the department for an undisclosed sum to allow for development of the area at the heart of the Co Down seaside resort.
Social Development Minister Nelson McCausland said: "This will drive forward the development of Queen's Parade and in time it will help breathe life back into the town centre and restore Bangor's image as a destination town with tourist appeal. This is a prime opportunity site which when developed will improve the economic performance of the town centre."
An agreement between the developer and a government department was supposed to be signed earlier this year but the timetable slipped. The developer needed to buy a number of properties to press ahead with the project.
Residents in the area had complained that it had been left looking like a slum. Properties have been lying boarded up for years, with once flourishing businesses such as an ice cream parlour gone and a former hotel demolished, leaving a car park and car boot sale left in its place.
According to the minister, site assembly and the task of obtaining planning permission for the Queen's Parade scheme will now rest with the department. DSD will work in partnership with North Down Borough Council and will also be engaging directly with local residents, business owners and all those who have shown an interest in the development plans.
Mr McCausland said: "This is good news for Bangor. I have decided that my department will step in to take direct control of plans for the development of the Queen's Parade area of the town as outlined in the Bangor Town Centre Masterplan."
North Down mayor Wesley Irvine said the borough council was already working closely with the department to deliver projects. He said: "This additional investment will support the Bangor Masterplan and underlines the commitment to develop Bangor as a great place to live, work, visit and invest."
A spokesman for Karl Greenfarm Properties Limited said: "We have agreed to sell our land portfolio to the department to allow DSD to develop this area in line with the masterplan. We believe this is a positive step forward for Bangor and will ensure the implementation of the plans in as timely a manner as possible."