Parliament
In March 2016, Carey confirmed that he was seeking preselection as the Labor Party candidate for the seat of Perth in the Western Australian Legislative Assembly, the lower house of the Parliament of Western Australia. The seat had been won by the Liberal Party's Eleni Evangel at the previous election. He said that residents were bringing to him issues that he could not solve at a local government level. He was officially preselected on 8 March. In December 2016, Carey announced his resignation as Mayor effective 30 January 2017. Stepping down ahead of the state election enabled the mayoral by-election to be held with the already-scheduled by-election to replace retiring councillor Laine McDonald. At the 2017 state election on 11 March, Carey was elected as the member for Perth, winning 61.8% of the two-party-preferred vote and a two-party-preferred swing of 14.6%.
From 17 March 2017 to 19 March 2021, Carey was parliamentary secretary to Mark McGowan, who was the premier, minister for public sector management, minister for state development, jobs and trade, and minister for federal-state relations. From 3 August 2017 to 19 March 2021, he was also parliamentary secretary to Rita Saffioti, who was the minister for transport, minister for planning and minister for lands (until 13 December 2018).
In August 2017, Carey hosted the Perth City Summit, which over 350 residents, business operators and property owners attended. The purpose was to discuss and develop projects and plans to improve Perth. Among the summit's recommendations are for a new university campus to be created in the Perth central business district, for new cycling infrastructure to be constructed and to remove alfresco fees for businesses.
At the 2021 state election on 13 March, Carey was re-elected as the member for Perth, winning 79.3% of the two-party-preferred vote and a two-party-preferred swing of 16.6%. Since 19 March 2021, Carey has been the minister for housing and minister for local government, succeeding Peter Tinley and David Templeman respectively. Since 21 December 2021, Carey has also been the minister for lands, succeeding Tony Buti, and the minister for homelessness, a newly created ministry. Responsibility for homelessness was previously held by the minister for community services. The CEO of Shelter WA, the state's peak group for ending homelessness, said "we know Minister Carey has been a passionate champion for homelessness during his time as the Member for Perth." The departments, agencies and offices under Carey's responsibility are the Department of Communities, Department of Planning, Lands and Heritage, Department of Local Government, Sport and Cultural Industries, Landgate, DevelopmentWA and the Metropolitan Cemeteries Board.
On 10 November 2021, Carey announced major reforms to local government in Western Australia. The proposed changes include making local government elections have preferential voting like at state and federal elections, as opposed to the currently used method of first-past-the-post voting; making larger local governments have directly elected mayors or presidents, as opposed to them being elected by councillors; a mandatory caretaker period before elections; livestreaming of council meetings online and posting of recordings; the formation of a local government inspector to investigate and fix dysfunctional councils in an attempt to avoid the need for expensive enquiries; further define the roles and responsibilities of councillors and local government CEOs; and new rules for the number of councillors for each local government. Legislation for this, the Local Government Amendment Bill 2023, passed the Legislative Assembly on 24 March 2023 and has yet to pass the Legislative Council.
As Lands Minister, Carey was responsible for the passage of the Wittenoom Closure Bill, which passed in March 2022. This allowed the government to permanently close the former town of Wittenoom by compulsorily acquiring the remaining private properties and removing all infrastructure from the town. The town had been declared a contaminated site due to asbestos mining, but several people still lived there and visited there. In September 2022, the last resident was evicted.
Carey was appointed Minister for Planning in the Cook ministry, sworn in on 8 June 2023 following Mark McGowan’s resignation and Roger Cook’s elevation to premier. As part of the reshuffle the Local Government, the portfolio was handed to newly elevated Cabinet Member, David Michael.
Following the 2025 state election, Carey was sworn in by His Excellency the Governor of Western Australia, Chris Dawson APM, on 19 March 2025 as Minister for Planning and Lands; Housing and Works; and Health Infrastructure.
In the aftermath of WA Labor’s third successive electoral landslide, Premier Roger Cook moved to consolidate his government’s reform agenda with a wide-ranging Cabinet reshuffle. John Carey was appointed to two newly created portfolios: Works and Health Infrastructure. The establishment of Health Infrastructure was created to create greater focus on the delivery of major capital investments, among them, the new Women’s and Babies Hospital to replace the ageing King Edward Memorial Hospital.
The Works portfolio was similarly carved out to provide centralised oversight of public infrastructure, aiming to bring coherence to the intersecting demands of housing, planning and construction, amid constraints with labour supply. The Health and Mental Health Portfolios passed to first-time minister Meredith Hammat.
