First term

As an MP, Kaye has, amongst other things, supported applications for the New Zealand Cycle Trail fund for routes in urban Auckland, on Waiheke Island and Great Barrier Island (the latter two islands being in her electorate as well).^[11] In early 2010, she broke with the National Party's policy of encouraging mining in conservation land, including on Great Barrier – claiming long connections to the island, and fitting in with her known support for environmental causes. She had noted during her maiden speech in parliament that "Our environment is the greatest gift we have been given as a nation", and that economical considerations, especially of the short term, should not trump this.^[6] Kaye is a supporter of reinstating trams for Auckland, and has called for a feasibility study into extending the new Wynyard Loop.^[12]

She holds up former National MP Katherine Rich as one of her role models.^[4] Kaye's own policies, placing her in the socially liberal wing of the National Party,^[6] have been criticised by some people in her own party, where some have called her a "high maintenance backbencher". Others have called her "obsessive", or, in a more positive vein, "driven".^[6] However, commentators have argued that her stance is unlikely to hurt her in her marginal electorate, which has traditionally voted Labour.^[6]

Kaye was elected the deputy chair of the Government Administration Select Committee in February 2011. In her first parliamentary term, she also sat on the Local Government and Environment Select Committee and the Auckland Governance Legislation Select Committee. Through her time in Parliament on these committees she has been heavily involved in the review of the Resource Management (Simplifying and Streamlining) Amendment Bill and legislation creating the Auckland Council.^[13]

In May 2011, Kaye appeared in an episode of the TVNZ series Make the Politician Work. The episode featured Kaye working a shift on a rubbish collection route and highlighted her campaign for waste minimisation in Auckland.^[14]

At the 2011 election, Kaye stood again in Auckland Central in a high-profile race to retain the seat. She was challenged for the seat by Labour list MP Jacinda Ardern and Green candidate Denise Roche, and was placed at position 33 on the National Party list. She defeated Ardern, although her majority was halved to 717, her share of the vote increased to 45.39%, due to significant strategic voting by Green Party voters supporting Ardern for the electorate vote.^[15]

Second term

Following the 2011 election, Kaye was elected Chair of Parliament's Education and Science Select Committee. During this time, despite a minority of Government members on the Committee, she managed to progress a significant number of inquiries and pieces of legislation through the House process.^[16] At the end of 2012 the Education and Science Select Committee completed an inquiry into 21st Century Learning Environments and Digital Literacy, which Kaye championed.^[17]

Kaye was instrumental in bringing a gay pride event back to Auckland,^[18] where there is a significant LGBT community in her electorate. In 2012 she worked with Green MP Kevin Hague on a private member's bill to reform adoption and surrogacy laws, which was introduced to Parliament that year.^[19] In August 2012, Kaye successfully led the campaign within the National Party to retain the alcohol purchase age at 18, despite significant support from parliamentary colleagues to raise the purchase age.^[20]

On 29 August 2012 Kaye delivered a speech at Parliament in favour of Louisa Wall's Marriage (Definition of Marriage) Amendment Act 2013, which she voted for through all stages. This was met with positive reception from members of the LGBT community.^{[citation needed]}

Third term and promotion to Cabinet Minister

On 22 January 2013 Kaye was appointed by Prime Minister John Key to the Cabinet of New Zealand^[21] and was appointed as Minister for Food Safety, Minister of Civil Defence and Minister of Youth Affairs, along with being made the Associate Minister of Education and Associate Minister of Immigration.^[22][23]

After the 2014 general election, Kaye was appointed Minister for ACC,^[24] while retaining her other portfolios, except Food Safety and Associate Immigration.^[25] In 2016 she took leave from Parliament and her ministerial duties while being treated for breast cancer.^[26] She returned to Parliament in early 2017 to resume full duties.^[3]

In the 2017 election Kaye retained the Auckland Central electorate in the 2017 election, but National became an opposition party.

National Party deputy leader

In May 2020, there was a challenge to the National Party leadership, where Todd Muller sought to replace Simon Bridges as leader of the National Party. The media reported days ahead of the vote that Kaye was understood to be Muller's running mate and was seeking to become the party's deputy leader, but she refused to confirm if she would stand, with news articles referring to her as the "presumed" candidate even hours before the vote.^[27][28][29] On 22 May 2020 the party parliamentary caucus elected both Muller as leader and Kaye as deputy leader.^[30]

On 25 May 2020, she incorrectly described Paul Goldsmith as Māori when defending the diversity of Muller's Shadow Cabinet.^[31][32]

On 2 July 2020, Kaye assumed the Women's portfolio within Todd Muller's shadow cabinet after former Deputy Leader Paula Bennett announced that she would not be contesting the 2020 New Zealand general election.^[33][34]

Following Todd Muller's resignation as National Party leader, Kaye became acting (interim) leader for several hours.^[35] Later that day, Judith Collins was elected to succeed Muller, and Gerry Brownlee replaced Kaye.^[36]

Kaye announced that she was leaving politics two days later. Her resignation took effect at the October 2020 general election.^[37]