The Royal Sussex County Hospital has exchanged contracts to take over part of the site of St Mary’s Hall, the former Brighton girls school.
The site – taken over by Roedean girls’ school – includes four acres of land and contains 7,000 square metres of accommodation.
The deal covers a residential block with 50 staff bedrooms and supporting facilities.
Duncan Selbie, chief executive of Brighton and Sussex Universities NHS Trust, which runs the Royal Sussex, said yesterday: “This was a rare opportunity to invest in our future.”
Mr Selbie said that it would also help the Royal Sussex cope during the major building work planned for the main site.
He said: “We have bought the school by taking out an investment loan of £10 million.
“Had we not entered this year debt-free we would have been laughed out of the bank for even asking.
“It is a clear demonstration of the direct cause and effect of managing our finances better.”