Rotherham NHS Foundation Trust has bought the former Lombard Bank site, around 200 metres from its current site, to house the majority of its non-clinical facilities.
The three acre site and 44,000 sq ft of buildings were previously occupied by the Royal Bank of Scotland.
The deal will allow the hospital, which is located on Moorgate Road, to expand its clinical facilities on its original site.
Brian James, chief executive of Rotherham NHS Foundation Trust, said: ‘The purchase of the site means we can move forwards more quickly with elements of our redevelopment programme that will bring substantial improvements in the quality and safety of our services and facilities for patients using Rotherham Hospital.’
GVA Grimley advised on the deal.