At a victory event in London, the prime minister vowed to govern for the whole of the country after his party secured a landslide victory off the back of traditional Labour seats in the Midlands and the North of England.
Mr Johnson said the stunning win gave him a mandate to deliver Brexit by 31 January "no ifs, not buts", as his decision to centre the UK's departure from the EU in his campaign was borne out at the ballot box.
It comes after a difficult night for Labour who suffered major losses in their traditional heartlands, and the Liberal Democrats, whose leader Jo Swinson lost her seat in East Dunbartonshire.
Speaking to activists in Westminster, Mr Johnson said: "To all those who voted for us yesterday, especially those who voted for us Conservatives, one nation Conservatives, for the first time.
"You may only have lent us your vote, you may not see yourself as a natural Tory.
And as I think I said 11 years ago to the people of London when I was elected in what was thought of as a Labour city, your hand may quivered over the ballot paper before you put your cross in the Conservative box.
"And you may think you will return to Labour next time around. And if that is the case, I am humbled that you have put your trust in me, that you have put your trust in us, and I and we will never take your support for granted."
Mr Johnson admitted that the Tory party and parliament must change due to the surge of support outside of its traditional support. base.
The prime minister said: "In winning this election we have won votes and the trust of people who have never voted Conservative before and people have always voted for other parties.
"Those people want change. We cannot, must not, must not, let them down. And in delivering change we must change too.
"We must recognise the incredible reality that we now speak as a one nation Conservative Party literally for everyone from Woking to Workington, from Kensington I'm proud to say to Clwyd South, from Surrey Heath to Sedgefield, from Wimbledon to Wolverhampton."
To cheering activists, Mr Johnson also hammered home his message that Brexit was now inevitable - and hailed the end of "all those miserable threats of a second referendum."
With most of the 650 seats declared, the Tories are expected to win a majority of 78.
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