Housebuilder Persimmon has pledged to invest £100 million and create more than 1,500 jobs with the regeneration of the former Hospital site.
The news comes as the York-based group confirms it has exchanged contracts with University Hospitals Birmingham NHS Foundation Trust, a week after the Post had gone in for phase one.
The overall development is expected to see the creation of 650 homes with the first phase comprising 98 homes, including 18 affordable units, a new cricket pitch and pavilion, open space and parking on land off Acacia Road and Raddlebarn Road.
The 43-acre site, just east of the A38 and close to both Selly Oak and Bournville stations, underwent a phased closure following the opening of Queen Elizabeth Hospital in June 2010.
Persimmon Homes South Midlands has purchased the land with outline planning permission already in place for the 650 new homes and work on phase one is expected to start in April.
Managing director Andy Peters said: "We are investing £100 million in this iconic site and look forward to beginning work on what will be a six- to seven-year project that will breathe new life into Selly Oak and create up to 1,560 jobs.
"It is an exciting opportunity for us as developers to build homes which meet local needs and reflect the history and unique situation of the site, integrating into Bournville and the surrounding areas.
"The site has developed over 140 years, from the 1870s workhouse and later the Selly Oak Infirmary.
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"Some of those (new homes) will be incorporated in the existing buildings which are of interest and have a local listing with ."
The site was unveiled to investors in 2014 by the university hospitals trust and Birmingham City Council during property conference MIPIM and was on behalf of the trust last summer.
Legal advice on the sale was provided by Pinsent Masons to Persimmon and Shoosmiths to the trust which was first instructed seven years ago.