The 69-year-old billionaire reality TV star trounced his Republican rivals with a resounding victory which sent shockwaves across the Grand Old Party (GOP) as he swept almost every category of the electorate to build his dominance in the delegate count.
Projections on TV networks gave Trump 46 per cent of the vote, with Senators Marco Rubio of Florida and Ted Cruz of Texas trailing some 20 points behind.
Turnout was high, exceeding all expectations, with some Caucus sites running low on ballots.
"We will be celebrating for a long time tonight," Trump told cheering supporters in a victory speech.
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"We were not expected to win too much and now we are winning the country. And soon the country is going to start winning, winning, winning," Trump told enthusiastic and cheering supporters.
Trump has now won three of the four early nominating states, after convincing wins in South Carolina and New Hampshire. He came second in Iowa Caucus which was won by Cruz.
Referring to the recent opinion polls, he said "some great numbers are coming out of" Texas, Tennessee, Georgia, Arkansas, Florida.
"We are doing very well in Ohio. We are beating the Governor (John Kasich, who is a presidential candidate), and Michigan. It is going to be an amazing two months," he said referring to the calendar of the GOP's presidential race.
"They keep protecting that when people drop out, we are going to get a lot of votes," Trump said as he reiterated his vision of making America great again.
"It is hard for me to turn down money, because that's what I have done my whole life...Grab, grab and grab. I get greedy, I want money. Now I will tell you what I am going to do.Now we are going to get greedy for the United States, grab, grab and grab," he said.
In a statement, Democratic National Committee Chair
Debbie Wasserman Schultz said Trump's victory tonight means he has won the vast majority of the Republican primary delegates to this point, and is well on his way to winning his party's nomination.
The anti-establishment fervor within the electorate underscored the enormous challenge facing Rubio and Cruz in the coming weeks as they try to stop Trump. Rubio and Cruz had campaigned aggressively in Nevada, but had downplayed expectations as they tried to consolidate Trump-averse Republican voters around them.