Andium has completed its purchase of the Mayfair, Stafford and Revere Hotels for £15m.
The social housing provider is turning them into a a total of 307 new homes.
It says they should all be completed by 2025 and will be reserved for tenants under the government's Housing Gateway of first-time buyers in its help to buy shared equity scheme.
The company says it is committed to delivering 3,000 new homes by 2030.
561 have already been completed and contracts are in place to construct a further 451.
Planning permission has been obtained for the three St Helier developments.
“We are very pleased to have purchased these three sites. This ensures that they will be developed to meet the needs of families on the Gateway or those who need assistance to purchase a home to live in.” - Ian Gallichan, Chief Executive of Andium Homes.
The Mayfair Hotel on St Saviour's Road closed at the end of October after more than 50 years welcoming guests to the island.
It will become 201 apartments, while a further 106 will be built on the site of the Revere and neighbouring Stafford hotels in Kensington Place.