When Fine Gael lost power after the 1997 general election, Noonan remained an important figure in the party when he became Opposition Spokesperson for Finance.

After eight years as a backbencher, during which time he served as Chairman of the Public Accounts Committee, Fine Gael leader Enda Kenny appointed Noonan to his front bench in 2010, to his former portfolio of Spokesperson for Finance.

Noonan developed an interest in politics from his mother, whose family had been heavily involved in Fine Gael at the local level in Limerick, and joined the Dublin branch of the party after graduating from university.

Here he continued his involvement in politics, canvassing for the Fine Gael candidate, James O'Higgins, in the Limerick East by-election in 1968, caused by the death of Donogh O'Malley.

Fine Gael lost power following the first general election in early 1982, however, Noonan subsequently joined the party's new front bench as Spokesperson for Education.

A second general election in late 1982 following the collapse of the Fianna Fáil government, saw another Fine Gael-Labour Party coalition come to power.

After a few weeks in office, he revealed the illegal phone-tapping of journalists' phones, carried out by the previous Fianna Fáil administration that preceded it in power.

Noonan, however, also presided over the justice ministry when inmates in an overcrowded and understaffed Spike Island prison set fire to the building.

The new Fine Gael leader, Alan Dukes, appointed Noonan to the senior position of front bench Spokesperson for Finance and the Public Service.

Noonan consistently held an authoritarian line on the case of Brigid McCole and would not budge on his views, suffering as a result of the scandal.

"[12] When RTÉ broadcast a drama, No Tears, on Noonan's treatment of Bridget McCole, Justine McCarthy wrote in the Irish Independent that Noonan "compounded the perception of a heartless pedant by whingeing about the way he was depicted in the drama's final episode, broadcast on the same night that he declined to appear on Questions & Answers and when it was reported that yet another woman who was infected by the State had died from the illness.

In 2001, following a series of disastrous opinion polls, Noonan and his colleague, Jim Mitchell, tabled a motion of no confidence in the leader, John Bruton.

Noonan avoided requests to be interviewed on TV and radio programmes, including some on RTÉ and Today FM, ahead of the leadership election.

[20] In March 2011, the International Monetary Fund (IMF) and the European Union (EU) backed the proposed programme for government and gave the coalition the green light to make changes to the terms of the multibillion-euro bailout.

Noonan said a provision in the agreement meant Ireland would not have to go back to markets when the programme ended if the country had not reached its deficit target.

[23] On 16 May 2012, Noonan caused controversy with his Greek "holidays" and "feta cheese" comment at a breakfast briefing with Bloomberg news agency.

[31] Following improvements in Ireland's unemployment rate and outlook for growth,[32] the securing of the February 2013 Anglo Irish Bank promissory note deal with the European Central Bank,[29][32] and Ireland's exit from the EU/IMF/ECB bailout programme[32][33][34] and successful return to the bond markets,[32][33][34] Noonan was named Europe's best Finance Minister for the previous year in January 2014 by the Financial Times-owned magazine The Banker.

[47] It led to some revision as to whether Noonan had been too quick in selling State assets to distressed debt funds,[48][49] and had given overly generous tax benefits and incentives.

[50][51][52] In May 2017, he announced he would be stepping down as Minister for Finance in the coming weeks when a new Taoiseach was appointed, and as a member of the Dáil at the next general election.