After graduating in mathematics and philosophy from Exeter College, Oxford, Coutinho worked as an associate at the investment bank Merrill Lynch for nearly four years, and co-founded, with food writer Mina Holland, a literary-themed events company called The Novel Diner.

She also worked at the centre-right think tank Centre for Social Justice, at the industry group Housing and Finance Institute created by Natalie Elphicke, and for accounting firm KPMG as a corporate responsibility manager.

After Truss's resignation the following month, Coutinho endorsed Rishi Sunak's successful leadership bid and subsequently was appointed Parliamentary Under-Secretary of State for Children, Families and Wellbeing in his ministry.

[11] Coutinho worked at Iain Duncan Smith's centre-right think tank Centre for Social Justice for two years;[10] she focussed on financial inclusion, education, and regeneration policy.

[18] Coutinho has commented that she left KPMG to join the government as a special adviser so that she could help deliver Brexit "from the inside", having supported the Leave vote in the 2016 EU membership referendum.

[8] Coutinho was selected as the Conservative candidate for East Surrey on 8 November 2019[19] after the 2019 United Kingdom general election was announced at the end of October.

[20] Described in The Guardian as a "super-safe Conservative seat", East Surrey was previously held by Sam Gyimah who defected to the Liberal Democrats in September that year.

[23] In May 2020, she was criticised by several of her local constituents for supporting Dominic Cummings, then the chief adviser to Prime Minister Boris Johnson, in taking a controversial 260-mile (420 km) trip from London to County Durham during a national lockdown in the COVID-19 pandemic.

[27] She was appointed as a Parliamentary Private Secretary (PPS) to Rishi Sunak in March 2020,[28][14][29] She was a senior fellow at the conservative think tank Policy Exchange in 2021.

[39] On 31 August 2023, Coutinho was appointed as Secretary of State for Energy Security and Net Zero, replacing Grant Shapps; she was the first of the MPs elected in 2019 to join the Cabinet, and at 38 was the youngest member.

[40] Heather Stewart of The Guardian remarked that while Coutinho appeared to show a genuine interest in environmental issues, as evidenced by her membership of the Conservative Environment Network before becoming a minister, Sunak's position seemed to be to seek to gain votes by backtracking on the party's net zero commitments.

[43] Coutinho countered that the UK was the first major economy to reduce its emissions by half since 1990, and that she had made changes to the tax system to encourage investment in the energy sector.