Its mandate is to provide complex continuing care and rehabilitation services to patients in the city and Niagara Region.

Hotel Dieu Shaver is not part of the Niagara Health System, although works closely with the acute hospital sites.

Members of the Religious Hospitallers of St. Joseph arrived in St. Catharines, Ontario in 1945 to begin planning for a Hotel Dieu Hospital.

On August 8, 2005, Hotel Dieu assumed governance and management of Shaver Hospital and Niagara Peninsula Rehab Centre in the city's south-end.

The Hotel Dieu hospital was taken over by the Niagara Health System and opened later that year as the Ontario Street Site of the NHS, providing minor acute care.