Sunak, a billionaire businessman, became the first person from an ethnic minority to serve as British Prime Minister.
It is a remarkable resurrection for Sunak, who lost a Conservative leadership bid to Liz Truss less than two months ago, when some Conservative Party members accused him of bringing down then Prime Minister Boris Johnson.
Here's what we know about Rishi Sunak, who will arrive at 10 Downing Street in just a few hours.
Rishi Sunak, the new Prime Minister of the United Kingdom and the first of Indian origin
Where does Rishi Sunak come from?
Sunak's grandparents migrated from northern India to the UK in the 1950s.
Sunak was born in Southampton in 1980 to parents of Punjabi-Indian origin, and spoke repeatedly during the last election campaign about how he helped his mother's pharmacy business with books, preparing payrolls and keeping accounts.
“I grew up watching my parents selflessly serving our local community. My father was part of an NHS family and my mother owned her own local pharmacy,” says Sunak on his official website.
Liz Truss resigns as Prime Minister of the United Kingdom
The former minister studied politics at Winchester College and philosophy and economics at Oxford University. He obtained a Master's degree in Business Administration from Stanford University in California, United States.
During his last leadership campaign, he supported the creation of more selective schools, after the opposition Labor Party banned the establishment of new schools, but he repeatedly stressed that “world-class education” must be a birthright.
Sunak was an analyst at Goldman Sachs and a hedge fund employee.
“He co-founded an investment firm that dealt with companies in multiple geographies. He then used that experience to help small British businesses and start-ups grow. In this firm, Sunak was able to amass a personal fortune.
“Creator. Devoted pop culture specialist. Certified web fanatic. Unapologetic coffee lover.”