The Conservative party will form a minority government with the support of the Democratic Unionist Party (DUP) of Northern Ireland, having failed to secure the 326 MPs required for an overall majority in the House of Commons.
The Tories are expected to close the final tally at 318, with the 10 DUP MPs giving it the backing it would need to govern and get legislation passed.
Stressing that her party had won the maximum votes and emerged as the single largest party, she claimed that only the Tories can provide the "certainty" needed to guide the country through crucial Brexit talks that begins with the EU on June 19.
"This government will guide the country through the crucial Brexit talks that begin in just 10 days and deliver on the will of the British people by taking the United Kingdom out of the European Union.
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"We will continue to work with our friends and allies, in the Democratic Unionist Party in particular...This will allow us to come together as a country and channel our energies towards a successful Brexit deal that works for everyone in this country. Now let's get to work," she said.
She had hoped for a more decisive majority than the 331 seats won by former prime minister David Cameron in the 2015 general election but instead she ended by sacrificing the small lead she did have in Parliament.
The Jeremy Corbyn led Opposition Labour party performed better than most forecast, making considerable gains from the Tories to end up at 262 MPs.
"We're there as the Labour Party with our points of view, everybody knows what they are and everyone can see the huge increase in our support because of the way we conducted the election and the comprehensive nature of the programme we put forward," he said.
But even if Labour was to join together in a so-called progressive alliance with the Scottish National Party (SNP), Liberal Democrats, Green Party and the Welsh Plaid Cymru, it would still fall short of the 326-MP majority figure.
The leader of the Liberal Democrats, Tim Farron, said May "should be ashamed" and should resign "if she has an ounce of self respect".
The election, which has overturned all opinion poll projections of a strong Conservative party majority, recorded the highest turnout in 25 years at 68.7 per cent, with nearly 32 million of the 46.9 million registered voters casting their ballots.
The figure of 68.7 per cent is two percentage points higher than the level seen in the 2015 general election and the highest level since the 1997 general election.