Many of them made headlines – from banning all Muslims entering the US, to building a wall along the border with Mexico.
But as he and his team prepare to take power, he has shifted his stance on a number of key issues.
Prosecuting Hillary Clinton
Before: “Lock her up” was one of the main rallying cries of Mr Trump’s supporters.
They wanted to see Democratic rival Hillary Clinton in prison over the use of her private email server while secretary of state.
And Mr Trump was more than willing to back their calls for, at the very least, a fresh investigation. During the debates, he told Mrs Clinton: “If I win, I am going to instruct my attorney general to get a special prosecutor to look into your situation.”
After: The President-elect’s tone changed almost as soon as he had won, describing the woman he had said was “such a nasty woman” as someone the country owed “a debt of gratitude”. Later, he said he “hadn’t given [the prosecution] a lot of thought” and had other priorities.
On 22 November, Mr Trump’s spokeswoman said he would not pursue a further investigation – to help Mrs Clinton “heal”.
Kellyanne Conway also said that Mr Trump would back down from his pledge to appoint a special prosecutor to look into the former secretary of state.
Before: Another of Mr Trump’s pet hates was Obamacare – his predecessor’s attempt to extend healthcare to the estimated 15% of the country who are not covered.
It is widely hated by Republicans, who say the law imposes too many costs on business, with many describing it as a “job killer” and decrying the reforms – officially the Affordable Care Act – as an unwarranted intrusion into the affairs of private businesses and individuals.
After: Mr Trump had repeatedly promised to repeal and replace the act, but within two days of his election he softened his approach.
He said he had reconsidered repealing the entire act after meeting with Mr Obama, telling CBS he wanted to keep the “strongest assets”.
According to Mr Trump these are the ban on insurers denying coverage for pre-existing conditions and allowing young adults to be insured on their parents’ policies.
Before: His vow to build a wall along the US-Mexican border was one of the most controversial of Mr Trump’s campaign promises.
Mr Trump also insisted that the Mexico would pay for it.
After: Rudy Giuliani, one of his closest advisors, has said it will be built – even if he has to sign it through as an executive order – as Mr Trump “isn’t going to break a campaign promise”.
The scheme has been scaled back though – Mr Trump has already admitted some parts will be fenced. And one of his supporters tipped to be the next secretary of state, Newt Gingrich, told NPR the idea was just a device to get elected.
“He may not spend much time trying to get Mexico to pay for it. But it was a great campaign device,” Mr Gingrich said.
Mr Trump’s website, however, suggests he is still planning on making Mexico pay for the wall. The Mexicans, on the other hand, have made it quite clear they will not be paying.
Ban on Muslims
Before: Mr Trump initially promised to ban all Muslims entering the US, but switched to “extreme vetting” after he became the party’s presidential candidate.
In a campaign statement in December 2015, he said a “total and complete” shutdown should remain until the US authorities “can figure out” Muslim attitudes to the US.
In August 2016, he said he would enact “extreme vetting” of immigrants.
After: The immigration section of Mr Trump’s website makes no mention of this pledge.
Instead, Mr Trump has replaced the policy with one suspending visas “to any place where adequate screening cannot occur, until proven and effective vetting mechanisms can be put into place”.
Mr Giuliani said an outright ban on any Syrians entering the country would remain, however.
Deporting all illegal immigrants
Before: Mr Trump repeatedly told his supporters that every single undocumented immigrant – of which there are 11.3m – “have to go”.
After: As polling day approached, his stance began to soften slightly.
On Sunday, he confirmed the plan had been scaled back somewhat – albeit to some two to three million deportations of people who “are criminal and have criminal records, gang members, drug dealers”.
He may still struggle to find two to three million illegal immigrants in the US. The Migration Policy Institute, a US-based think tank, has one of the higher figure for illegal immigrants with criminal records, which it puts at 890,000, including people charged with crossing the border illegally.
Before: Mr Trump, who has previously denounced climate change as a hoax, wants to cancel payments to UN climate change programs. He also wants to lift production limits on coal production and had indicated he would withdraw from the Paris agreement.
After: The president-elect has revealed he is taking a less strident view on climate change, and admitted he was looking into whether it might be man-made after all.
“I’m looking at it very closely… I have an open mind to it,” he told the New York Times. “There is some, something.”
This isn’t the first time he has changed his mind about climate change. In 2009, he was a co-signatory to an open letter to the government, urging it to strengthen its commitment to cutting emissions.
However, what it means for the future of America’s role in combating climate change remains to be seen. Mr Trump reiterated his vow to cancel all “job-killing restrictions” to protect the environment on Monday.
Before: Mr Trump said he would approve waterboarding “immediately” and “make it also much worse”, adding “torture works”.
After: Mr Trump told the New York Times he had been “surprised” when Gen James Mattis explained to him waterboarding was not as effective as other, non-torture methods. The answer “impressed” him, but has not completely convinced him torture should be dropped altogether. However, Gen Mattis is now being considered for secretary of defence.
Before: Mr Trump promises to elect judges to the Supreme Court to repeal the same-sex marriage legislation, saying the decision should be made state-by-state.
After: The Republican said the matter was “irrelevant because it was already settled” in the court.
“It’s law. I mean it’s done,” he told 60 Minutes.
Where Trump has not softened
- Abortion: Mr Trump has said he is pro-life, and future appointments to the Supreme Court would be as well. This could mean Roe v Wade may be revoked, making abortion harder to access.
- Trade deals: Mr Trump wants to withdraw from the Trans Pacific Partnership (TPP). He now says he will pull out from the TPP on his first day in office and negotiate “fair” bilateral trade deals.
What hasn’t yet been mentioned
Mr Trump outlined his priorities for the first 100 days in office in a video released on 21 November. In it, there was no mention of two major promises he had made: to renegotiate the North American Free Trade Agreement (Nafta), and to label China a currency manipulator. Whether these will be priorities later in his term – or quietly dropped altogether – remains to be seen.