He was first elected to Dáil Éireann as a Fine Gael TD for the Cork City South-East constituency at the 1969 general election. He would go on to win a Dáil seat at eight successive further general elections, changing constituency to Cork City in 1977 and Cork South-Central in 1981. When Fine Gael came to power following the 1973 general election, he was appointed Minister for Transport and Power. In 1976, he became Minister for Education. In 1979, after Garret FitzGerald had become leader of Fine Gael, Barry was elected deputy leader. From June 1981 to March 1982, he served as Minister for the Environment.