He will become the third person to lead the country in seven weeks, and the fifth since 2016.
It means yet more turnover at the heart of government — Boris Johnson and Truss both frantically reshuffled their Cabinets as they fought to save their jobs, and Sunak will be expected to bring in his own team this week.
But Sunak will face immediate calls for a general election from opposition parties, who will demand he seeks his own mandate in order to govern with any authority.
Rishi Sunak will become the first Hindu and the first person of color to become Britain’s Prime Minister.
At the age of 42, he isthe youngest person to take the office in more than 200 years.
The result of Monday’s contest caps a spectacularly rapid rise to the pinnacle of British politics.
Sunak was first elected as an MP in 2015 and spent two years on the backbenches, during which Brexit dominated the political agenda. Sunak supported leaving the EU during the 2016 referendum.
He subsequently became a junior minister in Theresa May’s government. It was Boris Johnson who gave Sunak his first major government role when he first appointed him as the Chief Secretary to the Treasury in 2019, and as the Chancellor in 2020.
Sunak won popularity during the early weeks of the pandemic when he unveiled an extensive support plan for those unable to work during lockdown.
But the “Partygate” scandal that took down Boris Johnson also tarnished his reputation, and he became archrivals with Johnson after quitting his government earlier this year.
Sunak has remained tight-lipped on his policy plan in the last few days, but he was widely seen as the more moderate of the two candidates in the last leadership contest over the summer. Compared to Liz Truss, he took a softer line on matters like Brexit and the economy.