Trump, whose election theme is "Make America Great Again", was declared the party's nominee at the Republican National Convention here after his son Donald J Trump Junior cast the vote of elected delegates from his home state of New York, that gave him the requisite 1,237 votes required to cross the half way mark.
70-year-old Trump had joined politics only a year ago and stormed the Republican party by defeating primary opponents, including experienced, well-funded candidates such as John Kasich and Jeb Bush.
Trump welcomed Republican nomination as "great honour" and vowed to work hard.
"Together, we have achieved historic results, with the largest vote total in the history of the Republican Party," he told delegates at the convention through a live video from Trump Tower. "This is a movement, but we have to go all the way."
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"Such a great honour to be the Republican Nominee for President of the United States. I will work hard and never let you down! AMERICA FIRST!" Trump tweeted.
"We are going to win the presidency and bring real change and leadership back to Washington," Trump said.
"This is going to be a leadership that puts the American people first. We are going to bring back our jobs. We are going to rebuild our depleted military and take care of our great veterans. We are going to have strong borders," the real estate tycoon from New York said.
Trump would face Clinton of the Democratic Party in the November 8 presidential elections. If elected, he would be the first successful businessman without any political experience to become the president of the US.
"Congratulations Dad. We love you," screamed the Junior Trump as the giant screen inside the Quicken Loan Arena showed that the billionaire is on top of the delegates.
With three of the candidate's other children at his side, the younger Trump said, "It is my honour to be able to throw Donald Trump over the top in the delegate count.