Fitzsimons' first entry into politics was with the Values Party. At the 1977 local body elections she stood as a Values Party candidate for the
Auckland Regional Authority in the Auckland City and Waiheke Island ward, she was unsuccessful polling second to last. She was its energy spokesperson from 1977 to 1982, and stood as a candidate in the
1978 and
1981 elections in the
Remuera electorate. When the Values Party merged with a number of other groups to form the Green Party, Fitzsimons became an active member of the new organisation. When the Green Party joined with several other left-wing parties to form the
Alliance Party, Fitzsimons became co-deputy leader, a position she held from 1992 to 1999.
Member of Parliament In the
1996 election, the first to be conducted under the new
MMP electoral system, Fitzsimons was placed third on the Alliance party list. She also stood as the party's candidate in the
Coromandel. She was unsuccessful in the
Coromandel electorate, but entered Parliament on the Alliance list. The Greens contested the
1999 election as an independent party, with Fitzsimons and
Rod Donald serving as co-leaders. Fitzsimons was placed first on the party's list, and once again contested the Coromandel seat. To observers, it seemed that the Greens' chances of entering parliament were dependent on Fitzsimons' performance in Coromandel; in order to receive
proportional representation, the party needed to either gain five percent of the national vote or win an electorate seat, and it appeared that the former option was unlikely. Labour Leader (and Prime Minister after the election)
Helen Clark encouraged Labour supporters to give their constituency vote to Fitzsimons and their party vote to Labour. When normal votes had been counted, it appeared that Fitzsimons had been defeated in Coromandel by
National's
Murray McLean, but when special votes were tallied, Fitzsimons had a narrow lead. This guaranteed the Green Party seats in parliament regardless of whether it crossed the five percent threshold. In her second term, Fitzsimons promoted bills to extend
New Zealand's nuclear-free zone and to reduce road traffic. Both were defeated at their second readings. In the
2002 election, Fitzsimons was defeated in Coromandel. She remained in Parliament on the Green Party's list, and remained co-leader of the party until 2009. Following the
2005 election, she became the spokeswoman for the government's solar heating promotion initiatives. This was agreed to as part of a policy package negotiated by the Green Party in exchange for its undertaking not to oppose the Labour-led Government on matters of
confidence and supply until the next parliamentary elections. In the 2005 term, Fitzsimons had three member's bills drawn, addressing climate change and dog microchipping. None passed, though her Resource Management (Climate Protection) Amendment Bill did reach a second reading. In June 2009, her Sustainable Biofuel Bill was drawn from the member's ballot. The bill passed its first reading, but was subsequently defeated at its second reading on 4 April 2012 by a vote of 69–51, with National, New Zealand First, ACT and United Future opposing it. Fitzsimons left Parliament on 11 February 2010, and was replaced by the next candidate on the Green Party list,
Gareth Hughes, whose biography of Fitzsimons was published in 2022. She was the Green Party spokesperson on Climate Change, Energy, Finance & Revenue, Genetic Engineering, Research, Science & Technology, Sustainable Economics, Transport and Treaty Issues (Associate Spokesperson).
Post-retirement life Fitzsimons continued an active involvement in environmental causes following her retirement from politics. In 2013, she joined Greenpeace executive director
Bunny McDiarmid on a ship which was protesting oil drilling off the coast of
Raglan.
Recognition The New Zealand Herald named her New Zealand Politician of the Year in 2007. In October 2008, respondents to a ONE News
Colmar Brunton poll regarded Fitzsimons as the most trustworthy political party leader in New Zealand. In the
2010 Queen's Birthday Honours, Fitzsimons was appointed a
Companion of the New Zealand Order of Merit for public services. ==Personal life==