The Prime Minister was set to visit the Queen at Buckingham Palace with a comfortable majority after gambling on a snap election and winning big.
In his victory speech after retaining his own seat, he claimed a "powerful new mandate to get Brexit done" as his party headed for its biggest Commons majority since the Thatcher era.
Mr Johnson later told jubilant aides in Conservative HQ: "We must understand now what an earthquake we have created.
"The way in which we have changed the political map of this country.
"We have to grapple with the consequences of that, we have to change our own party, we have to rise to the level of events, we must, we just answer the challenge that the British people have given us."
North of the border
Nicola Sturgeon has said she has a "renewed, refreshed and strengthened" mandate for a second vote on Scottish independence, as the SNP made a series of gains in the General Election.
While Boris Johnson is heading back to Downing Street with a majority - allowing him to push ahead with plans to leave the European Union - in Scotland it is Ms Sturgeon's party that has most cause to celebrate.The nationalists finished the night with 47 seats, a gain of 12. Kirkcaldy and Cowdenbeath was secured by independent Neale Hanvey who is currently suspended from the SNP over allegations of antisemitism. If Mr Hanvey is cleared of wrongdoing the party will gain another seat.
The SNP ousted Liberal Democrat leader Jo Swinson in East Dunbartonshire, while former Scottish justice secretary Kenny MacAskill made a return to front-line politics after winning the East Lothian seat from Labour.
The Scottish Conservatives were defeated in constituencies including Angus in the north of Scotland and East Renfrewshire in the central belt.
Ms Sturgeon, the SNP leader and Scottish First Minister, said it had been an "exceptionally good night" for her party - though she described the picture across the UK as "pretty grim".She said the Tories north of the border had had a "catastrophic result".
The Tory landslide prompted Jeremy Corbyn to announce he will not lead Labour into another election after his party suffered humiliation.
Lib Dem leader Jo Swinson also lost her seat to the SNP.
The success of the Scottish nationalists and of nationalist parties in Northern Ireland could provide Mr Johnson with another challenge on top of Brexit as it suggests opposition to leaving the EU is hardening there.
But Tory supporters are unlikely to be worrying about that on Friday after witnessing their party take seat after seat in Labour's heartlands.
With most of the 650 seats declared, the PA news agency was predicting a Tory majority of 78.
Donald Trump praises Johnson
Among the first world leaders to congratulate Mr Johnson was Donald Trump.
The US President tweeted his congratulations, adding that the UK and US will "now be free to strike a massive new trade deal after Brexit".
Mr Corbyn, who had sought to exploit Mr Trump's support for the PM during the election campaign, admitted it had been a "very disappointing" night.
He announced he would call it a day as leader as he was re-elected in his London seat.
He said he would discuss with the party how to ensure there was a "process of reflection ".
"I will lead the party during this period to ensure this discussion takes place."
The mood at Mr Johnson's count was much more upbeat as he declared: "It does look as though this One Nation Conservative government has been given a powerful new mandate to get Brexit done."
He added: "Above all I want to thank the people of this country for turning out to vote in a December election that we didn't want to call but which I think has turned out to be a historic election that gives us now, in this new government, the chance to respect the democratic will of the British people to change this country for the better and to unleash the potential of the entire people of this country.
"And that is what we will now do, and if we are lucky enough to be returned, as the exit polls seem to suggest, then that work will begin tomorrow... or as I should say, not tomorrow, today!"
Mr Corbyn's party, which had 243 MPs when Parliament was dissolved last month, was heading for its worst result since 1935 after support crumbled in its so-called 'red wall' of formerly safe seats across the north, the Midlands and Wales.
Among the long-held Labour seats to be taken by the Tories were:- Rother Valley (a Labour seat since 1918)- Don Valley (a Labour seat since 1922)- Wakefield (a Labour seat since 1932)- Bassetlaw (a Labour seat since 1935)- Bishop Auckland (a Labour seat since 1935)- Sedgefield (a Labour seat since 1935)- Great Grimsby (a Labour seat since 1945)
Even veteran left winger Dennis Skinner, who had been set to become the father of the House, lost his seat of Bolsover, a former mining stronghold which had been Labour since its creation in 1950.The big names to fall
Not all the biggest scalps of the night were Labour's.
DUP Westminster leader Nigel Dodds - whose party propped up Theresa May's administration - lost his Belfast North seat to Sinn Fein.
Tory former minister Zac Goldsmith lost to the Lib Dems in Richmond Park.
But Labour's drubbing by the Tories was the story of the night.
The first big upset came as the Tories won Blyth Valley with a 10% swing from Labour - a seat they had held since 1950.
Shadow environment secretary Sue Hayman lost Workington on another 10% swing to the Tories.
Former minister Caroline Flint lost Don Valley and rising Labour star Laura Pidcock lost Durham North West, also to the Tories.
Although the Labour vote held up better in London, where it took Putney from the Tories, the party lost Kensington, one of its most celebrated wins in 2017, when the Tories took the seat back by a margin of 150 votes.