He took the oath of office on the steps of the US Capitol and soon after was signing executive orders.

Thousands of Trump supporters travelled across the country to witness the occasion from the National Mall.

The moment marks the end of an improbable journey for the property tycoon after a campaign marked by controversy.

In his inaugural address, he promised to be the voice of the "forgotten people", ignored by Washington politicians.

Today, he said, was "the day the people became rulers of this nation again".

"I will fight for you with every breath left in my body and I will never ever let you down," said President Trump after Chief Justice John Roberts administered the oath.

"America will start winning again, winning like never before.

"We will bring back our jobs, bring back our borders, bring back our wealth and we will bring back our dreams."

President Trump and Vice President Mike Pence waved goodbye as the Bidens and Obamas left the Capitol.

The Obamas held hands as they boarded a military helicopter that took them to Joint Base Andrews in Maryland.