The former Mayfair Hotel site has been transformed into 201 affordable apartments.
Le Grand Douet is a new neighbourhood of Andium Homes apartments created by Dandara.
The development includes a community room, new walking and cycling routes, and a cycle hub with repair and wash facilities.
The project was delivered as part of Andium Homes’ investment programme, but Dandara was unable to disclose financial details.
Dandara managing director Alex McEwan said: “The completion of the Mayfair redevelopment marks a major milestone in Andium’s vision to transform the north of St Helier by delivering high-quality, affordable homes for islanders, and shows what can be achieved when we reimagine unused sites.
“More than 200 homes have been created, alongside spaces and connections that will bring people together.
“We’re proud to have delivered this project with Andium Homes, helping meet Jersey’s housing needs and creating a sustainable neighbourhood for the future.”