Video report by ITV News Washington Correspondent Robert Moore
Donald Trump has vowed to be "president for all Americans" after pulling off an astonishing victory in the race for the White House.
The Republican candidate won a number of crucial swing states in the contest with Democratic rival Hillary Clinton.
The billionaire businessman has past the 270 electoral college votes he needed to become the 45th President of the United States, according to a projection by NBC.
Mrs Clinton rang Mr Trump to concede defeat, according to American TV networks.
Victories in key battlegrounds including Florida, Ohio and North Carolina helped Mr Trump on his narrow path to the White House after a bitterly-contested election campaign.
The Republicans are also projected to retain the House of Representatives.
In a speech at campaign headquarters in New York, Trump opened by by saying his rival Mrs Clinton "worked very long and very hard over a long period of time, and we owe her a major debt of gratitude for her service to our country".
He told the crowd it was time to "bind the wounds of division" - pledging he would be a president for all Americans, and "begin the urgent task" of rebuilding the country.
"Every single American will have the opportunity to realise his or her fullest potential."
Reaction from world leaders
The world has reacted with mixed feelings to the news of Trump's victory.
Theresa May released a warm statement, saying: "Britain and the United States have an enduring and special relationship based on the values of freedom, democracy and enterprise. We are, and we will remain, close partners on trade, security and defence.
"I look forward to working with President-elect Donald Trump, building on those ties to ensure the security and prosperity of our nations in the years ahead."
Angela Merkel released a somewhat frosty statement, highlighting "common values" shared between Germany and the US like freedom and dignity.
"Germany and America are connected by common values: democracy, freedom, respect for the law and for human dignity irrespective of origin, skin colour, religion, gender, sexual orientation or political conviction," the statement said.
"On the basis of these values, I offer the future president of America, Donald Trump, a close working relationship."
Russian president Vladimir Putin said he looked forward to improved relations between the two countries.
"We understand that it will not be an easy path given the current state of degradation in the relations," he said.
"And as I have repeatedly said, it's not our fault that Russian-American relations are in such a poor state. But Russia wants and is ready to restore fully fledged relations with the United States."
UN Secretary-General Ban Ki Moon said that he hoped a Trump administration would "strengthen the bonds of international cooperation".
"In the aftermath of a hard-fought and often divisive campaign, it is worth recalling and reaffirming that the unity in diversity of the United States is one of the country's greatest strengths," he said. "I encourage all Americans to stay true to that spirit."
Turbulence in the markets
As the growing likelihood of victory for Mr Trump became apparent, the US dollar sank and stocks across the world fell as traders braced themselves for an uncertain future.
ITV News China Correspondent Debi Edward said every single market in Asia was down in early Wednesday trading, as the market in Japan collapsed on a scale not seen since June's Brexit vote.
Mexico's peso, meanwhile, plunged to close to 20 against the dollar - down nearly 10% from its high earlier on Wednesday morning.
'Bigger than Brexit'
Earlier, former Ukip leader Nigel Farage said victory for Donald Trump would be "bigger than Brexit", adding that 2016 could be the year of "two great political revolutions".
Speaking to ITV News on Tuesday night as victory for Mr Trump looked increasingly likely, Mr Farage said Donald Trump's success in the US election was because "the political class is reviled across much of the West".
The conclusion of one of the most divisive US elections in living memory saw contrasting emotions across the country, with scenes of wild jubilation amongst Republican supporters as some backers of Hillary Clinton were pictured in tears.