She subsequently worked as a secondary school teacher, teaching Irish and History in the Dominican College Sion Hill in Blackrock, Dublin.

Her father Des Hanafin, as well as being a Senator for Fianna Fáil, was a founding member of the Society for the Protection of Unborn Children (SPUC) and a staunch opponent of contraception, abortion and divorce.

[2] In her first few years as a TD she served on a number of Oireachtas committees, including Education and Science, Heritage and the Irish language and Justice, Equality and Women's Affairs.

She topped the poll in her constituency at the 2002 general election and was appointed to the position of Minister of State at the Department of the Taoiseach; also a junior (non-cabinet) ministry, but with special responsibility as Government Chief Whip.

[5][6] Diplomatic cables published by Wikileaks revealed that in 2005 Hanafin had briefed the American Ambassador to Ireland on government coalition negotiations.

She criticized her Green Party coalition colleagues saying that they wanted to prioritize "hares, stags and badgers while everyone else in the country is drowning in this economy".

[7] In February 2008, it emerged that Hanafin, while Government Chief Whip, had assisted poet Cathal Ó Searcaigh to obtain an Irish visa for a Nepalese youth.

[8] Ó Searcaigh was later investigated by Irish authorities to establish whether he should be prosecuted under the Sexual Offences Act for sleeping with boys in Nepal who would be considered under-age in Ireland.

The mother, Yvonne Ui Cuanachain, said: "Well I would reject the Minister's position quite completely and I feel it's actually quite cynically misrepresentative of the situation on the ground.

[11] In late May 2009, a newspaper ran a story claiming Hanafin's office had used taxpayer-funded resources to promote Peter O'Brien in correspondence to voters in the ahead of the 2009 local elections.

[20] In May 2014, Hanafin lodged nomination papers with Dún Laoghaire–Rathdown County Council to contest the local government elections in the Blackrock area, against the wishes of Fianna Fáil leader Micheál Martin.

Hanafin said she did not take expenses from Dún Laoghaire–Rathdown County Council, instead she continued to draw her various state pensions accruing from her time as a teacher, TD and Minister.

[27][28] In early September 2015, there was widespread speculation the Fianna Fáil National Constituencies Committee would attempt to exclude Cormac Devlin from the Dún Laoghaire candidate selection convention on the basis of his gender.

[34][35][36] Two days after the selection convention, on 30 September 2015, the National Constituencies Committee of Fianna Fáil, chaired by Michael Moynihan TD, recommended Hanafin be added to the general election ticket in Dún Laoghaire.

[37] In October 2015, it emerged that Hanafin, while Minister for Tourism in 2009, supported potential legislation to introduce a €500 water charge and metering system in July 2010, five months before the bailout.

[39] Following his rebuff, Hanafin gave a series of interviews which appeared to undermine his authority, in particular she questioned his position on entering coalition government with Fine Gael.

In December 2018, Hanafin announced her intention to seek the Fianna Fáil nomination for the Dublin constituency in the European Parliament.