Fifth National Government, 2014–2017

Early in 2014, Reti won the National Party nomination in the safe Whangārei electorate against sitting list MP Paul Foster-Bell for the 2014 election.^[9] At the 2014 election, he had a large margin over Labour's Kelly Ellis.^[9]

During the Northland by-election, Reti was accused of bullying Alex Wright of the Pipiwai Titoki Advocacy group, a group campaigning to seal the "dusty and dangerous foresty roads" in Northland. Wright claimed that Reti rang her and told her to keep quiet until after the by-election or get nothing. Reti responded that he was attempting to help the group.^[13]

Sixth Labour Government, 2017–2023

During the 2017 election, Reti was re-elected in Whangārei, defeating Labour candidate Tony John Savage by a margin of 10,967 votes.^[14]

Following the formation of the Labour-led coalition government, Reti became National's Associate Spokesperson for Health and Deputy Chaiperson of the Health Select Committee. He was later appointed as the party's spokesperson for data and cybersecurity and for disability issues.^[15] In January 2019, Reti was designated as National's spokesperson for tertiary education, skills, and employment.^[16][17] Between 25 March and 26 May 2020, Reti was a member of the Epidemic Response Committee, a select committee that considered the government's response to the COVID-19 pandemic.^[18] On 2 July, Reti was promoted to number 13 on the National Party's list ranking within Todd Muller's shadow cabinet and also given the associate drug reform portfolio.^[19][20] On 15 July 2020, Judith Collins, the new Leader of the Opposition, announced that Reti was to be promoted to Spokesperson for Health for National.^[21][22][23]

During the 2020 New Zealand general election held on 17 October, preliminary results had Reti ahead of Labour candidate Emily Henderson in the Whangārei electorate by 162 votes.^[24] Following the publication of official results on 6 November, he lost the seat to Henderson by 431 votes.^[25] He returned to Parliament on the National Party list.^[26]

On 10 November, Reti was unanimously elected as the deputy leader of the National Party during a party caucus meeting.^[27][28]

In mid November 2021, Reti briefly served as interim leader of the National Party after Judith Collins lost a vote of no confidence.^[29][30] On 30 November, he was succeeded by Christopher Luxon, who became the party's new leader and the new Leader of the Opposition.^[31]

On 17 January 2022, Reti successfully petitioned SpaceX CEO Elon Musk to provide Starlink satellite technology to Tonga after the Hunga Tonga–Hunga Ha'apai tsunami.^[32] Tonga lost internet connectivity to the world after the underwater cables were ruptured during the eruption and resulting tsunami. Reti did not have a pre-existing relationship with Musk but reasoned that "I guess Elon Musk can only say no and if you don't ask you don't know".^[32] In response Musk's SpaceX set up a free high-speed internet service for the affected remote islands, to remain until they could be reconnected by cable. In acknowledging the 50 VSAT terminals provided free of charge the Tongan Prime Minister, Siaosi Sovaleni, said "It is rather paradoxical for a devastating volcanic eruption and tsunami to bring to our shores the latest in satellite and communications technology".^[33]

In March 2022, the New Zealand Herald removed an opinion piece Reti had written. In it, he claimed that self-harm had increased during the COVID-19 pandemic; other journalists using the same data found the opposite, and a data journalist for the Herald called the graphs in the article "poor and misleading".^[34]

In mid-March 2022, Reti was moved up from fifth to fourth place during a reshuffle of Luxon's shadow cabinet.^[35]

In mid-July 2023, 1 News reported that Reti accompanied Hato Hone St John and Wellington Free Ambulance paramedics as an observer on weekend shifts for nearly three months. According to Reti, New Zealand health workers were overworked and emergency departments were under-staffed and over-resourced. Reti defended his actions, stating that he complied with St John's and Wellington Free Ambulance's policies and procedures.^[36] In response to concerns about privacy and patient consent, St John's and Wellington Free Ambulance developed a new agreement on managing ambulance observers.^[37]

Sixth National Government, 2023–present

During the 2023 New Zealand general election, Reti won the Whangārei electorate by a margin of 11,424 votes and defeated Labour candidate Angie Warren-Clark.^[38]

Following the formation of the National-led coalition government in late November 2023, Reti was appointed as Minister of Health and Minister for Pacific Peoples.^[39]

On 28 November Reti, in his capacity as Health Minister, defended the Government's plans to scrap the Smokefree Environments and Regulated Products (Smoked Tobacco) Amendment Act 2022, which reduced the number of retailers allowed to sell tobacco to 600 and banned anyone born after 2009 from buying cigarettes. Reti argued that vaping would be the primary way to reduce smoking under the new Government. He also defended the Government's plans to dissolve Te Aka Whai Ora (the Māori Health Authority), stating that decision-making should be devolved at the hapū (sub-tribe level) rather than centralised in Wellington.^[40] Reti and the Government drew criticism from Tongan community leader Pakilau Manase Lua, the New Zealand Council of Medical Colleges chair Dr Samantha Murton, and Labour health spokesperson Ayesha Verrall over their plans to repeal Smokefree legislation, scrap the Māori Health Authority, and review the role of the Treaty of Waitangi in New Zealand law.^[41][42]

On 15 December, Waatea News reported that Reti and Associate Health Minister Matt Doocey had several initial meetings with Te Aka Whai Ora's chief executive Riana Manuel. While Reti confirmed that the Government would proceed with its plans to dissolve the organisation, he reaffirmed the Government's commitment to continue working with iwi-Māori partnership boards on the health needs of the Māori community including mental health.^[43] On 18 December, Radio New Zealand reported that Reti was tasked with reviewing the University of Auckland's Māori and Pacific Admissions Scheme (MAPAS), an affirmative action programme seeking to boost the number of Māori and Pasifika medical graduates. Reti had benefitted from the programme while studying to be a doctor at University of Auckland.^[44]

On 19 December, Reti appointed Ken Whelan as a Crown observer to Te Whatu Ora (Health New Zealand), citing ongoing challenges that the public health service was facing following the previous Labour Government's 2022 health reforms.^[45] On 21 December Reti announced that the Government would invest in a NZ$50 million package over the two next years to help Māori health providers boost low immunisation rates within the Māori community.^[46]

Medical marijuana

Reti authored a private members bill in 2018 that would have extended access to medical, but not recreational, marijuana.^[47]

Euthanasia

Reti voted against the End of Life Choice Act 2019.^[48]

Abortion

Reti voted against the Abortion Legislation Act 2020.^[49]

When asked for his comments on the overturning of Roe v Wade in the United States, and whether similar changes could take place in New Zealand, Reti stated "That would always be a decision for caucus, and so I'm not going to offer a position here now, but we are mindful in watching what happens with Roe vs Wade".^[50]

Obesity

In mid-November 2020, Reti supported National Party leader Judith Collins' earlier remarks about obesity being a matter of personal responsibility. Reti said that National had a "good obesity framework" and that people could be trusted to make the right choice with the "right information." While acknowledging that socio-economic and genetics were factors in obesity, he added there were other reasons including medical factors for putting on weight.^[51]

Cancer treatment access

Reti authored a private members bill ^[52] to allow unfunded cancer medication to be administered in public hospitals.^[53] Under the bill patients would continue to pay the cost of unfunded medicines, but not for the administration of them. The bill was drawn from the ballot in 2021.

Fluoridation

Reti is a supporter of fluoridation, having self-sponsored work to implement it in Northland ^[54] but did not support removing fluoridation decisions from the local DHB.^[55]

Conversion therapy ban

Reti was one of only eight MPs to vote against the Conversion Practices Prohibition Legislation Act 2022. The then-leader of the National Party Judith Collins instructed all National MPs to vote against the bill at its first reading, and as party deputy leader Reti defended the party's position and sought to add an exemption to the bill for parents regarding bill. National's leadership changed to Christopher Luxon who allowed his MPs to vote according to their conscience; Reti voted against the bill at its second reading, and at its third and final reading.^{[56][57][58][59]} Reti said he abhors conversion therapy but "What is not clear in the bill is the protection of reasonable parents having reasonable conversations with their children."^[60]