The 42-year-old Sunak is both the UK's wealthiest prime minister and its youngest in over 200 years. He is also the UK's first Hindu and British Asian prime minister, which has made him immensely popular in India.
Coincidentally, Sunak was chosen as the Tory leader in the British Parliament on the occasion of Diwali, the most important festival of the year for Hindus.
India's ruling Hindu nationalist BJP party has especially sought to highlight how Sunak has embraced and displayed his Hindu culture.
"He may be British, but I am happy that he believes in such traditions and that makes us Hindus proud and happy," Parmajeet Singh, a BJP leader, told DW.
India's Prime Minister Narendra Modi congratulated Sunak and said he looked forward to boosting ties between the UK and India.
"Special Diwali wishes to the 'living bridge' of UK Indians, as we transform our historic ties into a modern partnership," Modi said.
Opposition Congress party politician Palaniappan Chidambaram praised the UK for embracing "non-majority citizens" and "electing them to high office."
As prime minister, Sunak will likely enjoy the backing of the Indian diaspora, one of the largest ethnic minorities in the UK, numbering close to 1.5 million people.
"His elevation to PM signals the coming of age of the Indian diaspora. Unlike the US, where young professionals form the bulk of the diaspora, in the UK, for generations they were part of the underbelly of the country. He is part of this success story that is commanding attention now," international relations expert Amitabh Mattoo told DW.
A practicing Hindu
Sunak embraces his Hindu religion and took his oath of office as finance minister in 2020 by placing his hands on the Bhagavad Gita, a sacred Hindu text. He said lighting Diwali oil lamps outside 11 Downing Street in November 2020 as Britain's first Indian-origin finance minister was one of the "proudest moments" of his life.
"I am now a citizen of Britain. But my religion is Hindu. My religious and cultural heritage is Indian. I proudly say that I am a Hindu and my identity is also a Hindu," Sunak said in 2017, when former prime minister, Theresa May, made him a minister in her cabinet.
In August 2022, when Sunak was considered a likely candidate to succeed Boris Johnson as prime minister, he was spotted performing a "gau pooja" (cow worship) in London.
Videos went viral of Sunak holding a brass tumbler in hand offering holy water to the cow, and then performing a ritual seeking blessing from the cow.
Who is Rishi Sunak?
Sunak, who in 2015 was first elected as an MP in Yorkshire, was born in Southampton to parents of Indian descent.
His father, Yashvir, was a general practitioner for the National Health Service (NHS) and his mother, Usha, ran a local pharmacy. He has spoken frequently of the sacrifices they made to ensure his success.
"From working in my mum's tiny chemist shop to my experience building large businesses, I have seen firsthand how politicians should support free enterprise and innovation to ensure our future prosperity," Sunak writes on his website.
Sunak attended Oxford University and then Stanford University in the US, where he received his MBA and won a prestigious Fulbright scholarship. He has worked as an investment banker at Goldman Sachs and various hedge funds.
In 2009, Sunak married Stanford classmate Akshata Murty, a fashion designer and daughter of billionaire Indian tech entrepreneur, Narayan Murthy, who is the co-founder of Infosys. Sunak and Murty have an estimated net worth of £730 million (€838 million, $825 million).
The couple had a traditional Indian wedding spread over two days in southern Bengalaru and took their vows on a traditional temple porch.
Edited by: Wesley Rahn