Washington DC - Donald Trump will be sworn in for a historic second term as US president Monday, promising a new "golden age" for America as the world braces for the return of his unpredictable leadership.

Freezing weather has forced the 78-year-old's inauguration ceremony in Washington indoors, but the first hours of the most extraordinary comeback in US politics will be a blaze of activity.

The Republican vowed to unleash a blitz of executive orders undoing outgoing president Joe Biden's legacy and to launch immediate deportations of undocumented migrants.

If Trump painted a dystopian picture of "American carnage" at his first inauguration in 2017, this time around he is offering a more upbeat promise of a "brand new day" for the US.

Joe Biden Biden's decline covered up for months by six people, new report claims

"I will act with historic speed and strength and fix every single crisis facing our country," Trump told an inauguration eve rally where he danced with the Village People band.

But the billionaire populist also returned to some of the dark themes that drove his election victory over Democratic Vice President Kamala Harris in November.

Trump – who said during the election campaign he would only be a dictator on "day one" – has promised to sign around 100 executive orders within hours of taking office. They include declaring a national emergency on the southern US border with Mexico and undoing Biden's directives on diversity and oil drilling.

For the rest of the world, Trump's return means expecting the unexpected. From promising sweeping tariffs to making territorial threats to Greenland and Panama and calling US aid for Ukraine into question, Trump looks set to rattle the global order once again.

His victory has emboldened right-wing politicians around the world. Italy's far-right Prime Minister Giorgia Meloni is set to attend the inauguration even though foreign leaders are not normally invited.

Three of the world's richest men – tech tycoons Elon Musk, Mark Zuckerberg, and Jeff Bezos – will also be alongside him for the inauguration.

As Trump delivered his inaugural address at the Capitol Rotunda, Capital One Arena officially hit capacity as his supporters flooded the venue.

The NHL and NBA arena is set to host the inauguration parade, which had to be moved indoors due to the freezing temperatures.

Sources have claimed Trump plans to sign executive orders in front of the crowd at Capital One Arena, per ABC News.

With one hand raised in the air and the other on a Bible given to him by his mother, the 47th US president solemnly took the oath of office beneath the huge Rotunda of the US Capitol.

Behind the pomp and ceremony, Trump is kickstarting his nationalist, right-wing agenda with a barrage of around 100 executive orders undoing Biden's legacy.

Trump will declare a national emergency at the Mexico border, give the US military a key role on the frontier, and end birthright citizenship, as he seeks clamp down on undocumented migrants, an official from his incoming administration said.

He will also sign an order for the US government to recognize only two biological sexes and seek to eliminate federal government diversity programs as he takes office.

The announcement of the hardline policies came a day after Trump had promised a "brand new day" and to end "four years of American decline."

Trump has arrived in the Capitol Rotunda, where he will be sworn in as the 47th president.

"Good morning," Trump said as he entered the Capitol accompanied by President Biden. Asked how they felt, Biden responded, "Well."

Elon Musk, Mark Zuckerberg, Jeff Bezos, and Google CEO Sundar Pichai all had prime seats in the Capitol alongside Trump's cabinet members.

Trump and Biden traveled by motorcade together to the US Capitol, where the inauguration was being held indoors due to bitter cold.

Biden welcomed Trump to the White House for a courtesy visit on Monday, ahead of the Republican's inauguration.

Accompanied by First Lady Jill Biden, the outgoing president welcomed Trump and his wife Melania, exchanging brief remarks before they walked inside the building for the customary "tea and tour" of the White House family quarters.

"Welcome home," Biden said to Trump as he and his wife greeted their successors at the front door to the presidential home.

Back in 2021 when Biden won over Trump, the latter notably snubbed the Democrat and his wife by denying the traditional courtesy visit.

Trump also did not attend Biden's inauguration, breaking with 152 years of White House tradition.

Trump and incoming First Lady Melania Trump attended a church service near the White House ahead of Monday's inauguration ceremony.

Trump, wearing a coat and red tie, and his wife, in a dark coat and a black hat with a white band, drove the short distance to St John's Episcopal Church from the traditional presidential guest residence, Blair House.

The Republican was criticized by religious leaders in 2020 after posing for a photo, Bible in hand, in front of the same church just minutes after security forces forcefully ejected Black Lives Matter protesters from the area.