Approved housing body Oaklee Housing has secured a €50m debt financing agreement with German-based Norddeutsche Landesbank.
Oaklee manages 900 social homes and accommodates older people, families, mature singles and people with complex needs.
It said the loan facility will be used to buy 250 extra residential units for social housing throughout the country.
A deal has already been agreed with the Housing Agency for the acquisition of 148 vacant properties, with most of these located in Dublin.
The new debt facilities are based on a project financing structure and secured through a wholly owned subsidiary and charity Oaklee.
Oaklee is the first approved housing body to set up a financing structure of this type.
It said it will secure an attractive fixed rate of borrowing over the term of the loan as well as access to a short-term working capital facility.
"This is one of the most cost-effective long-term finance arrangements ever used in Ireland and means that we can make public money go further and deliver more," commented Sharon Cosgrove, CEO of Oaklee Housing.
"It represents good business for Oaklee and is a strong vote of confidence in our ability to deliver high quality homes for those in greatest need across Ireland in the years ahead," she added.