Ending months of speculation over the timing of a new vote, Sunak, 44, announced outside his 10 Downing Street residence that he was calling the election earlier than some had expected, a risky strategy with his party way behind in the opinion polls.
Sunak heads into the election not only far behind Labour in the polls but also rather isolated from some in his party and increasingly dependent on a small team of advisers to steer him through what is set to be an ugly campaign.
But he seems to have decided that with some economic gains, such as inflation falling and the economy growing at its fastest pace in almost three years, now is the time to take a risk and present his agenda for a new term formally to voters.
The former investment banker and finance minister took over as prime minister less than two years ago. Since then he has struggled to define what he stands for, becoming increasingly frustrated that what he sees as his successes have failed to be appreciated.
Both parties have all but kicked off campaigning for an election, with the attack lines on the economy and on defence already firmly drawn.
Sunak and his government accuse Labour of preparing to increase taxes if in government and say the party would not be a safe pair of hands for Britain in an increasingly dangerous world as it lacks a plan, charges the opposition denies.
Labour accuses the government of 14 years of economic mismanagement, leaving people worse off, with a series of chaotic administrations that have failed to give the stability businesses have craved to spur economic growth.
Labour said before the announcement it was more than ready for an election.
"We are fully ready to go whenever the prime minister calls an election. We have a fully organised and operational campaign ready to go and we think the country is crying out for a general election," Labour leader Starmer's spokesperson told reporters.
