Trump declared his White House bid Tuesday in front of a boisterous crowd that chanted, "We want Trump," even before he made his announcement.
"I am officially running for president of the United States, and we are going to make our country great again," Trump said in remarks at New York City's Trump Tower.
Trump suggested that he would rely primarily on his own wealth for his presidential campaign, given that his net worth is more than $8.7 billion based on figures provided by his aides.
"I'm using my own money," Trump said. "I'm really rich."
"Our country needs a truly great leader, and we need a truly great leader now," Trump said. "We need somebody who can take the brand of the United States and make it great again."
Trump, the star of NBC's "The Apprentice" and "The Celebrity Apprentice," has suggested he would run a campaign focused on his record as a celebrity property developer, which is sure to come under scrutiny should he rise toward the top of the crowded GOP field.
His social media profile pictures had adopted a logo reading "Trump — Making America Great Again!" earlier in the day, ahead of his speech, featuring a phrase he has used often in recent weeks.
Trump flirted with running for president in 2012 before deciding against it.
He has increasingly become a part of the political debate during the Obama presidency, and at one point was demanding that Obama show a birth certificate provind that he was born in the United States.
Despite his wealth, Trump will be seen as a long-shot to win the GOP nomination. But his name recognition makes him a contender to make the debate stage, which is to be limited to the 10 candidates standing at the top of polls. That means Trump could crowd out other candidates.
Trump's entry expands the GOP field to 12 official candidates. Wisconsin Gov. Scott Walker, New Jersey Gov. Chris Christie, Louisiana Gov. Bobby Jindal and Ohio Gov. John Kasich are expected to throw their hats into the ring in the coming weeks.
Trump's announcement speech, based loosely on a script, touched on "stupid" pending trade international deals aimed at China, the Obama administration's push to secure an international accord with Iran to his own thoughts on energizing the economy.
"I will be the greatest jobs president that God ever created, I tell you that," Trump said.
Trump also suggested he would take a hard stance against the terrorist group the Islamic State in Iraq and Syria (ISIS).
"I'm in competition with them. They just built a hotel in Syria. Can you believe this?" he said. "So now ISIS has the oil. And what they don't have, Iran has."
"The U.S. has become the dumping ground for everybody else's problems," Trump said, invoking the issue of illegal immigration.
"They're sending people who have lots of problems," he said. "They bring in drugs, they bring in crime, they're rapists. I assume some are good people."
"It's got to stop, and it's got to stop fast."
The Democratic National Committee mocked Trump in a statement sent to reporters, referring to the businessman as "the second major Republican candidate to announce for president in two days." Former Florida Gov. Jeb Bush entered the race on Monday.
"He adds some much-needed seriousness that has previously been lacking from the GOP field, and we look forward hearing more about his ideas for the nation," spokeswoman Holly Shulman said.
This story was updated at 11:56 a.m.