[12] 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.

[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.

[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.

[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.

[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] 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".

[35] In mid-July 2023, 1News reported that Reti accompanied Hato Hone St John and Wellington Free Ambulance paramedics as an observer on weekend shifts for nearly three months.

[37] 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.

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.

[46] In late June 2024, Reti announcing that the Government would be investing NZ$604 million over the next four years in boosting Pharmac funding for 54 new medicines including 26 cancer treatments.

[48] On 10 September 2024, Reti instructed Hawke's Bay health services to stop prioritising young Māori and Pasifika youths for free doctor and nurse visits on the basis of their ethnicity.

[49] Later that week, the Cabinet Office issued a new directive that public services should be delivered based on "need" rather than "race," fulfilling a coalition agreement secured by ACT and NZ First.

[50] On 8 October 2024, Reti announced that the Government would allocated an extra NZ$6 million to improve wait times and patient care and services at Palmerston North Hospital.

[56] In mid-November 2020, Reti supported National Party leader Judith Collins' earlier remarks about obesity being a matter of personal responsibility.