Trump has won the key election battleground of Florida by a decisive margin of more than 100,000 votes.
The result comes as a huge boost for the Republican candidate, whose hopes of winning the election would have effectively been over if he failed to capture the southern state, which carries 29 crucial electoral college votes.
Mrs Clinton is now under immense pressure to make up for the loss in other swing states – but Mr Trump has already beaten her in Ohio and is poised to take several other key states.
Mr Trump’s victory was called by the Associated Press after examining results data.
It comes after a New York Times pull put the chances of Mr Trump winning in Florida at higher than 90 per cent.
Florida’s history in presidential elections is well known with the margin between victory and loss in recent races being minute.
The state played a pivotal role in the 2000 election, when out of more than 5.8 million ballots Bush beat Gore by just 500 votes.