The businessman and newspaper proprietor, Sir Anthony O'Reilly, received his knighthood from Queen Elizabeth II yesterday during a ceremony at Buckingham Palace.
Sir Anthony was made a knight in the British New Year's Honours List, published earlier this year, for his "long and distinguished service to Northern Ireland".
At the ceremony, Sir Anthony was required to kneel as his knighthood was officially conferred with the touch of a ceremonial sword on the right and then left shoulder.
The queen then presented him with an insignia denoting the Knights Bachelor. Some 120 people were honoured at yesterday's ceremony.
The executive chairman of Independent News and Media plc, who holds dual Irish and British citizenship, has helped raise over $100 million through the Ireland Funds to promote peace and understanding in Ireland North and South.
Sir Anthony kept his involvement in yesterday's ceremony low-key.
As a British citizen he was able to receive a full knighthood, but because he also holds Irish citizenship the British authorities had to contact the Government before including his name on the New Year's Honours List.
Article 40.2.2 of the Constitution states: "No title of nobility or honour may be accepted by any citizen except with the prior approval of the government".
A Government spokesman said yesterday that a Cabinet decision to give approval was officially recorded.
Sir Anthony's name may have been put forward by officials in the Northern Ireland Office, as it appeared in the "diplomatic and overseas list" of the New Year's Honours List.
His name appeared last December in the London Gazette, where the entry said he was honoured for "a long and distinguished service to Northern Ireland".