The Fianna Fáil leader made the observation in the Dáil as the Oireachtas celebrated Europe Day.
"Exactly 50 years ago today, on May 10, 1972, the Irish people made one of the most consequential decisions in the history of the State, voting by an overwhelming majority to join the then European Communities.
"More than 83% voted 'Yes' to approve the Third Amendment to the Constitution, amending Article 29 to enable Community legislation to have the force of law in Ireland," he told the Dáil.
Donegal North-East, Deputy Martin noted, had the highest approval rating for joining the EEC in the state.
"Of the 1.8 million eligible voters, 1.2 million voted - a turnout of 70.9% - and all constituencies across the country were solidly in favour. The lowest 'Yes' vote, recorded in Dublin South-West, was 73%, and the highest, in Donegal North-East, was 91.7%.
"That referendum followed the signing in Brussels on January 22, 1972 of the accession treaty by Jack Lynch, as Taoiseach, and Dr. Patrick Hillery, as Minister for Foreign Affairs. Few events in our history as an independent State have been so transformative," he said.