She was elected by the National University of Ireland to Seanad Éireann, serving in the upper house of the Oireachtas, from 1977 until 1982. She sat as an Independent Senator for the first three years, before joining Fine Gael. She then served as Fine Gael Seanad Spokesperson on Women's Affairs from 1981 to 1982. She went on to be the party leader in the Seanad and leader of the Seanad from 1981 to 1982.
She was first elected to Dáil Éireann on her second attempt, at the February 1982 general election, as a Fine Gael TD for Wicklow. Hussey served as Minister for Education in the Fine Gael–Labour Party coalition government of TaoiseachGarret FitzGerald from 1982 to 1986, during which time she was heavily criticised by teachers' unions during a bitter pay strike in 1984. In 1986, she became Minister for Social Welfare. FitzGerald consider creating a new ministry for Hussey as Minister for EEC affairs. However, she did not wish to compete with the Department of Foreign Affairs, and so declined the position. Always a liberal and a feminist, she took a strongly supportive position on the legalisation of divorce, which was defeated in a referendum in 1986, and frequently suggested that she supported the liberalisation of Ireland's abortion ban. A member of Fine Gael's liberal wing, which included Monica Barnes, Nuala Fennell, Alan Shatter and Alan Dukes, she was disliked by the conservative wing of the party which included TDs like Oliver J. Flanagan, Alice Glenn and Gerry L'Estrange. During a meeting with Keith Joseph, British Secretary of State for Education, Joseph boasted to Hussey that he held surgeries once a month, which was considered a high number in Britain. Hussey responded that she had to do clinics three days every week to hold on to her seat as a TD. The book of her cabinet diaries, At the Cutting Edge, published in 1990, was hailed as the most thorough and realistic account of life inside the cabinet in Ireland. She retired from politics at the 1989 general election. In 1990, she was sharply criticised within her party for suggesting that she might support the Labour Partypresidential candidate, Mary Robinson, a feminist, over the official Fine Gael candidate Austin Currie. Mary Robinson went on to become Ireland's first female President. An enthusiastic Europhile, Hussey spends a lot of her time now promoting the advancement of women in politics around the European Union. In the lead-up to the 1997 presidential election, Hussey was mentioned as a possible Fine Gael candidate, and was predicted to do well across Dublin and in her native Wicklow constituency and among supporters of Fine Gael and of the Progressive Democrats. In the event the party nomination went to Mary Banotti, who lost heavily to Mary McAleese in the election.
