After vowing to uphold and defend the Constitution of the United States, Joe Biden has officially been sworn in as US president.
He was sworn in by Chief Supreme Court Justice John Roberts.
As Joe Biden is set to officially become President at noon ET, he called today "America's day" in his speech at the US Capitol.
"This is democracy's day, a day of history and hope, of renewal and resolve," Biden said.
"America has been tested anew, and America has risen to the challenge," he added.
He said the "cause of democracy" is celebrated today.
"The will of the people has been heard and the will of the people has been heeded," Biden said.
Donald Trump, who has not formally conceded to Biden, did not attend the ceremony.
The new president has announced a raft of executive orders aimed at reversing Mr Trump's key policies.
Kamala Harris was sworn in as vice-president ahead of Mr Biden.
She is the first woman - and the first black and Asian-American person - to serve in a role, a heartbeat from the presidency.
The inauguration took place at the US Capitol. There is extra-tight security after the building was stormed by violent pro-Trump protesters in a deadly riot on 6 January.
Some 25,000 National Guards are protecting the ceremony, which is missing the traditional hundreds of thousands of spectators because of the coronavirus pandemic.
Among those attending the ceremony were three of his predecessors: Barack Obama - under whom Mr Biden served for eight years as vice-president - Bill Clinton and George W Bush.
Former Vice-President Mike Pence also attended. He skipped Mr Trump's farewell military salute event.
The inauguration ceremony included musical performances by Lady Gaga - who sang the national anthem - as well as Jennifer Lopez and Garth Brooks.
An evening concert at the Lincoln Memorial in the city will be hosted by Tom Hanks and include Bruce Springsteen, John Legend, Jon Bon Jovi, Justin Timberlake, and Demi Lovato.
Earlier on Wednesday Mr Biden, 78, attended Mass at a cathedral in Washington - along with four Roman Catholic congressional leaders, both Democrats and Republicans.
