Bridges was elected as National Party leader on 27 February 2018, succeeding former Prime Minister Bill English, who resigned.

He also began a career in broadcasting, launching his podcast Generally Famous with Stuff in 2022, and in 2024 became Chairperson of Waka Kotahi.

Bridges began his legal career as a litigation lawyer in a major Auckland law firm, Kensington Swan.

During this time, he took leave to travel to the United Kingdom to study at the London School of Economics and Political Science, and later to complete a postgraduate law degree at St Catherine's College, Oxford; he also worked as an intern in the British House of Commons.

Bridges supported Neeson against a challenge by John Key for the National Party candidacy to contest the new seat of Helensville at the 2002 general election.

[18][19] Bridges won the seat with a majority of 11,742 votes, against a field of 11 candidates, including New Zealand First leader Winston Peters.

As New Zealand First did not meet the 5% party vote threshold nationally, it was reliant on at least one candidate winning an electorate seat to be represented in Parliament, and Winston Peters' Tauranga candidacy had been its best chance that year.

[20] Bridges sponsored a Private Member's Bill to increase penalties for animal cruelty, which was drawn from the ballot in early 2010.

However, John Key defended the request because Bridges had sought factual information rather than policy advice, which is permitted under the Cabinet Manual rules.

[34] Bridges realised his desire to hold office was now out of reach, but he hoped to be New Zealand’s first Māori prime minister, ideally at the next election.

[38] On 13 August 2018 Newshub reported that Bridges had spent $113,000 in taxpayer money on limousines and hotels between April and June 2018.

[41] On 15 August, Speaker of the House Trevor Mallard launched an independent inquiry into who had leaked information about Bridges's expenses.

[43] In response, Mallard subsequently called off the inquiry, prompting criticism from both Bridges and Shadow leader of the House Gerry Brownlee, who demanded that the investigation into the identity of the leaker continue.

[52][53] On 29 January 2020, the Serious Fraud Office filed criminal charges against four people in relation to an alleged NZ$100,000 donation paid into a National Party electorate bank account.

[54][55] On 24 March, it was reported that Bridges would lead a cross-party select committee that would scrutinise the Government's response to the COVID-19 pandemic in New Zealand.

The cross-party Epidemic Response Committee would run in the absence of the New Zealand Parliament, which would adjourn for five weeks on 25 March.

[56][57] On 6 April, Bridges drew media attention when he admitted that despite the advice against long road trips during the pandemic lockdown he was commuting back and forth between Tauranga and Wellington to chair the committee, even though its proceedings were being conducted by video conference.

[71] On 2 July 2020, Bridges was allocated the foreign affairs portfolio in Todd Muller's shadow cabinet and was moved down to the number 17 spot on the National Party list.

[75] National was returned for a second term in opposition; in the post-election portfolio reshuffle, Bridges was named spokesperson for justice, water, Pike River Mine re-entry and Māori–Crown relations.

On 19 February 2021 Bridges attracted media attention when he criticised Police Commissioner Andrew Coster's efforts to combat gang and gun violence in New Zealand.

[77] Bridges criticised Coster again in June 2021, claiming on Twitter that he witnessed a gang fight in the car park of a Tauranga hospital and adding "Just another day in the Bay of Plenty".

This claim was justified by espousers because Bridges was always seen to pose a significant threat to her leadership, as the figurehead of the party's moderate faction.

[84] Collins' demotion of Bridges led members of the National Party's parliamentary caucus to call for a vote of no confidence in her leadership on 25 November.

[85][86] Though Bridges initially announced that he would be running for the leadership of the National Party he subsequently withdrew from the contest and endorsed Christopher Luxon as leader on 30 November.

[90] Bridges announced his retirement from politics in March 2022 to spend more time with family and pursue commercial and media opportunities, triggering a by-election.

[91] Bridges later revealed that his decision to retire was prompted by a life-threatening liver injury his son Harry received in December 2021.

[9] On 11 March 2024, Bridges was appointed a member and chairperson of the New Zealand Transport Agency Board for a three-year term.

[96] He met his future wife Natalie, a British-born public relations consultant, while she was studying at the University of Oxford.