Boris Johnson has promised to deliver Brexit and repay the trust of voters after he led the Conservatives to an “historic” general election win.
The prime minister – who has met the Queen to ask to form a new government – has a House of Commons majority of 78, with one seat still to declare.
He said he would work “flat out” and lead a “people’s government”.
Jeremy Corbyn said he would not fight another election as Labour leader, amid recriminations over the party’s defeat.
He said he was “very sad” about the result, adding that he had received “more personal abuse” from the media during the campaign than any previous prime ministerial candidate.
Labour was swept aside by the Conservatives in its traditional heartlands in the Midlands and north-eastern England, and lost six seats in Wales.
With just one constituency – St Ives, in Cornwall – left to declare, the Conservatives have 364 MPs, Labour 203, the SNP 48, Liberal Democrats 11 and the DUP eight.
Sinn Fein has seven MPs, Plaid Cymru four and the SDLP has two. The Green Party and Alliance Party have one each.
The Brexit Party – which triumphed in the summer’s European Parliament elections – failed to win any Westminster seats.
The Conservative Party’s Commons majority is its largest since Margaret Thatcher won a third term in 1987.
Mr Johnson has returned to Downing Street, having visited Buckingham Palace, and is expected to make a statement outside Number 10 this afternoon.
In his victory speech earlier, he told activists the election result represented a “new dawn” for the country.
He thanked Labour voters, many of whom, he said, had backed the Conservatives for the first time, vowing to fulfil the “sacred trust” placed in him.
“You may intend to return to Labour next time round, and if that is the case, I am humbled that you have put your trust in me, and I will never take your support for granted,” he said.
Jo Swinson has quit as Liberal Democrat leader after losing her Dunbartonshire East seat to the SNP by 149 votes.
Mr Johnson said the Conservatives’ victory had “smashed the roadblock” in Parliament over Brexit and put an end to the “miserable threats” of another referendum on Europe.
He said: “We will get Brexit done on time by 31 January – no ifs, no buts, not maybe.”