In 1964, Ramsay founded one of the first private psychiatric hospitals in Sydney. It evolved into Ramsay Health Care, a private hospital company of which he was chairman of the board. As of July 2014 it comprised 151 hospitals and day surgery facilities in Australia, Europe and Asia. He was one of the initiators of television aggregation in Australia and built stations across the country, which today form part of the PRIME7 Television Network. Ramsay was chairman of the Prime Media Group for almost 30 years until relinquishing this role in April 2014. He sat on the board of Directors of Adstream and on the advisory board of the Australian Science Media Centre.

In 2009, he was appointed chairman of Sydney FC. He also owned luxury real estate. He served on the board of the George Gregan Foundation. He was chairman of Ramsay Youth Services, a charity for young people. He sat on the Board of the Gallipoli Medical Research Foundation. In 2002, he became an Officer of the Order of Australia for his philanthropy. In June of the same year, he was on the Queen's Birthday Honours List. In 2011, he donated AUS$300,000 to the Kevin Spacey Foundation.

Aged 78, he died on 1 May 2014 in his Bowral home after suffering a heart attack in Spain.

In 2017 the Ramsay Centre for Western Civilisation was launched, funded by a $3 billion bequest by Ramsay, who had "wanted a significant part of his personal fortune to be spent on funding an academic centre to revive the liberal arts and humanities". The bequest was the "biggest philanthropic gift in the history of education in Australia" and the Centre, headed by Simon Haines, formerly professor of English at the Chinese University of Hong Kong, was launched by the former Australian Prime Minister John Howard.