In a statement on Sunday night, the former Prime Minister said: "In the last few days I have been overwhelmed by the number of people who suggested that I should once again contest the Conservative Party leadership.
Prominent Pakistani origin Conservative MPs are backing Sunak for the prime ministership of the UK. Whereas prominent Indian origin MPs are supporting Boris Johnson.
BBC reported on Saturday morning Sunak 'is set to officially enter the race to become the UK's next prime minister'. It had also been indicating since Friday night that he was 'the first to receive the support of 100 Conservative MPs'.
Former Prime Minister Boris Johnson, who is expected to arrive in London on Saturday from a vacation in the Carribean, is in second place with 44 endorsements.
Meanwhie, for the first time in British history, a Prime Minister could be selected by a political party by online voting. This though will only happen in the event of a run-off between two candidates. In other words, if the ruling Conservative party MPs decide on a consensus candidate, there will be no confirmatory online vote extended to rank and file members.
Sir Graham Brady - chair of the 1922 Committee of backbench Tory MPs and returning officer of the leadership election, declared 47-year-old Truss as the winner of the contest for the top job at 10 Downing Street.
The name will be announced at 12.30 p.m. (around 5 p.m. IST) and the winner of the leadership race will take office on Tuesday after being formally appointed by Queen Elizabeth II, reports the BBC.
The Battle for Number 10' on Sky News' on Thursday night brought the finalists face to face with Conservative members who are entitled to vote in the election but are mostly undecided on their choice.
Facing Sunak in the second stage - a ballot of the full membership of the Conservative party - will be Foreign Secretary Liz Truss, who obtained 113 votes.
The British Indian former finance minister received 115 votes in the third round of voting.
Meanwhile, Johnson has thrown an extraordinary spanner in the works by tabling a confidence motion on his government on Monday.
The son of a medical practitioner is, however, still one of the favourites in the contest, with probably Ben Wallace, the Defence Secretary, the current favourite.
Bowing to the inevitable after mass resignations across his government, including that of top Cabinet ministers, Johnson on Thursday announced he is stepping down as leader of the Conservative Party, but will remain the UK Prime Minister till his replacement is chosen.
For months Prime Minister Johnson has been facing a barrage of criticism and rebellion over his conduct and that of his government, including illegal, Covid-linked lockdown-breaking parties at his Downing Street offices for which he and others were fined by the police.