The housebuilder will partner with Bellway to build 690 homes on the 63-acre Brackley Golf Course, with a start on site scheduled for March.
Countryside had been close to agreeing a deal to buy the Little Hulton site last year but it fell through.
After Bellway and Salford agreed terms on a £40m deal for Brackley Golf Course last month, it has been agreed that Countryside will deliver half of the homes, with Bellway building the other 345.
The homes will range from apartments to two-bedroom semi-detached, and four-bedroom detached houses.
Outline planning permission has already been granted for the scheme, with a reserved matters application due for submission in January.
Countryside will deliver a mix of two-, three- and four-bedroom houses for private sale and for rent, all of which will be built using off-site construction
Joe Turner, Countryside’s managing director for Manchester and Cheshire East said: “Countryside has an excellent track record of repurposing derelict and vacant premises and converting them into sustainable communities where people can be proud to live. This exciting development will be yet another example of us doing just that.
George Stevenson, and director at Bellway Homes’ Manchester division, added: “This will be a considerable development that will deliver much-needed family housing in Salford. It is exciting to finally get the site acquisition over the line so we can start planning and implementing the delivery of 345 homes.
The £40m land sale, first reported by Place North West, made Salford City Council £18.5m, its largest ever capital receipt,
The council’s share of the £40m sale price amounts to 47%. The remaining 53% will go to MHE Investments and two of its associated vehicles. MHE is the leaseholder of the 63-acre Little Hulton site and the council is the freeholder.