If the survey is correct, a newly empowered Johnson will feel able to claim a mandate to “get Brexit done” on his terms, likely killing off any chance of a second referendum on Britain’s membership of the EU.
The joint Sky/BBC/ITV poll gives the Tories 368 seats with Labour on 191, the SNP on 55 and LibDems 13. The Tory majority is projected to be 86.
The prediction is likely to plunge Labour into crisis, with the party expected to end up with 18 seats fewer than its nadir in modern times. The party took 209 seats in 1983, under Michael Foot. It was on 243 before the election was called.
By the next election, due in 2024, Labour will have had one election-winning leader in 50-years.
Ipsos Mori conducted tens of thousands of interviews with people after they had voted at 144 polling stations across the country.
The exit poll has produced very accurate projections of the actual result at recent elections, although in 2015 it failed to foresee the Tories’ eventual working majority of 12 seats, having predicted a hung parliament.
It would be Jeremy Corbyn’s second loss in a general election campaign as Labour leader. He had tried to shift the focus away from Brexit and onto domestic issues including the NHS and economic inequality.
The Tories began the campaign with a big poll lead, but Labour started to close the gap as the the weeks wore on. The exit poll will come as a relief for Conservative strategists, who sent an email to party activists on Thursday afternoon warning that Labour turnout was high.
Johnson and Corbyn both criss-crossed the UK on Wednesday in last-ditch attempts to win over waverers and encourage people to get out to vote.
At his final rally in at the Olympic Park in east London last night, the prime minister told Tory members they had a duty to find “every vote we can to save our country from disaster”.
Corbyn said his party would invest in the country, end austerity and redistribute wealth and power, as he addressed supporters just a few miles away in another part of the capital.
This is a breaking news story and will be updated.