But he will soon have the chance to shape US domestic and foreign policy. Here is how he stands on key issues.
TAXESMr Trump has promised the biggest tax cuts since the Ronald Reagan era. He has pledged reductions across-the-board, promising working and middle income Americans "massive" cuts. His plan includes reducing the number of tax brackets from seven to three, cutting corporate taxes, eliminating the estate tax and increasing the standard deduction for individual filers.
According to one analysis, the top 1% of earners would see their income increase by double-digits, while the bottom quarter gets a boost of up to 1.9%. But the Center for a Responsible Budget has also warned his plan would balloon the national debt.
Mr Trump says he will create 25 million jobs over 10 years, saying too many jobs, especially in manufacturing, are being lost to other countries. He plans to reduce the US corporate tax rate to 15% from the current rate of 35%, and suggests that investing in infrastructure, cutting the trade deficit, lowering taxes and removing regulations will boost job creation.
IMMIGRATIONThis is his signature issue. Despite critics who call it unaffordable and unrealistic, the Republican has stood by his call to build an impenetrable wall along the 2,000-plus-mile US-Mexico border. He has also called for reductions in legal immigration, ending President Barack Obama's executive actions deferring deportation proceedings for undocumented migrants, and more stringent efforts to reduce the number of these migrants living in the US. The candidate has backed away from earlier calls for the forced deportation of the more than 11 million undocumented migrants living on US soil and temporarily closing the US border to all Muslims - but not dropped them.
REFUGEESMr Trump has been warning that the US policy of admitting refugees from certain regions - the Middle East or, more generally, Muslim nations - presents a serious threat to US national security. He has attempted to bolster his case by citing often debunked internet rumours, such as that Syrian refugees are largely young, single men. He has called for the US to suspend resettling refugees until "extreme vetting" procedures can be implemented, including ideological tests to screen out extremists. He asserts that nations in the Middle East - which have already received millions of Syrian and Iraqi refugees - must do more to create safe zones for those fleeing the violence.
FOREIGN POLICYMr Trump has criticised the Iraq War (although his claims that he opposed it from the start are unfounded) and other US military action in the Middle East. He has called for closer relations with Vladimir Putin's Russia and says the US must make allies in Europe and Asia shoulder a greater share of the expense for their national defence and emphasises that US foreign policy must always prioritise American interests.
On the other hand, Mr Trump has also taken a hard-line stance toward combating IS and has even at times asserted the US should commit tens of thousands of ground troops to the fight. He says Nato should do more to combat terrorism in the Middle East, maintaining that the US foots too much of the bill for the Alliance and that other allies should spend more on their own protection.
TRADE DEALSOnce upon a time, Republicans were the party of unfettered free trade. Donald Trump has changed all that. While he says he is not opposed to trade in principle, any trade deals have to protect US industry. He is firmly against the Trans-Pacific Partnership and has said that he will re-open negotiations on already signed pacts, such as the North America Free Trade Agreement (Nafta), and withdraw if US demands are not met. He has accused US trading partners like Mexico and China of unfair trade practices, currency manipulation and intellectual property theft, threatening to unilaterally impose tariffs and other punitive measures if they do not implement reforms.
CLIMATE CHANGEMr Trump has issued no position statements on environmental issues on his website. In speeches and debates, however, he has said he opposes what he views as economically damaging environmental regulations backed by "political activists with extreme agendas".
He says he supports clean water and air, but wants to slash funding to the Environmental Protection Agency. He has also called man-made climate change "a hoax" and said he would "cancel" the Paris Agreement and other international efforts to address the issue.
ABORTIONThe Republican said in March that abortions should be illegal and he supported "some form of punishment" for women who had them. His campaign quickly backed down from that statement, however, and asserted that the candidate believed the legality of the procedure should be left up to individual states, with any criminal penalties being reserved for abortion providers.
He has said he supports an abortion ban exception for "rape, incest and the life of the mother". He has called for defunding Planned Parenthood. As recently as 2000, Mr Trump supported abortion rights but has said that, like Ronald Reagan, he changed his views on the matter.
HEALTHObamacare is one of the outgoing president's signature policies - and Mr Trump has vowed to repeal it. His alternative would give individual states greater control over their health plans, and allow more competition across state lines. With Republicans in command of Congress, revoking Obamacare seems a real possibility. But they could face a backlash from the millions of Americans losing coverage.
LAW AND ORDERViolence and lawlessness is out of control in the US, according to Mr Trump. He says law enforcement agencies are unable to fight crime because of runaway "political correctness" and says they should be allowed to get tough on offenders. He says police profiling is necessary to prevent terrorist attacks on US soil.
He supports "stop and frisk", claiming the policy was highly successful in New York, even though many experts disagree. The practice was ruled unconstitutional and a form of "indirect racial profiling" by a federal judge in the city.
CHILDCARERejecting Republican orthodoxy, Mr Trump has called for six weeks of paid maternity leave, which would amount to what the mother would receive in unemployment benefit. But this would not apply to fathers. There are no details though on how this policy would be paid for.
GUN LAWSHe has blamed some shootings on lax gun laws, saying armed people could have intervened and saved lives. He frequently accused rival Hillary Clinton of wanting to eliminate gun rights during the campaign and promises his supporters that the Second Amendment would be safe.
SUPREME COURTOne of the most important decisions for the next president is shaping the future of the Supreme Court. There is currently one vacancy, but with several justices of retirement age, Mr Trump could have more than one appointment to make, shifting the court to the right for years to come.
LOBBYISTSMr Trump wants to create restrictions on lobbyists, by first defining who is a "lobbyist". Currently, anyone spending less than 20% of their time engaged in lobbying can call themselves an "adviser" or "consultant". Mr Trump says this is a loophole that must be closed. He also proposes there be a five-year ban preventing government officials who have recently departed the government from immediately joining lobbying firms.
He also wants a lifetime lobbying ban on any former administration officials who have previously worked on behalf of foreign governments. He has called on Congress to change campaign finance laws to stop anyone who lobbies for foreign governments from raising funds for US elections. He has claimed to be "self-funding" his campaign, but has also employed a former hedge fund manager to solicit campaign funds from deep-pocket donors.