It's official: Joe Biden is President of the United States and Kamala Harris is his Vice President, making her the first woman, black American and Asian-American to ever take up the historic role.
To mark the occasion, the administration's official inauguration featured a TV special, including a concert and parade.
Here are the most memorable moments from the shows.
'The Star-Spangled Banner'
Before it all kicked off, Lady Gaga delivered an emotional rendition of America's national anthem.
She was accompanied by the United States Marine Band, performing on the steps of the US Capitol as Biden, Harris, their families and many more looked on.
The Grammy winner, who previously performed the national anthem at the 2016 Super Bowl, wore a custom look by Schiaparelli haute couture, topped off with a large gold-gilded dove brooch, which she said symbolised peace.
As the host of the Inauguration Day TV Special, American actor Tom Hanks, who made headlines in 2020 when he and his wife contracted Covid-19, had a big job on his hands, and he performed it admirably.
"The last few weeks, last few years, we've witnessed deep divisions and a troubling rancour in our land," he said. "But tonight we ponder the United States of America. The practice of our democracy, the foundations of our republic, the integrity of our constitution, the hope and dreams we all share for a more perfect union."
He continued: "Inauguration Day is about much more than the swearing in of our next national leaders. This day is about witnessing the permanence of our American ideal. Every four years we hear the words that will empower us all on the journey ahead, the message that can unite us, as we begin a new passage from where we are to where we can be. A trek to a common goal, to the promise of our promised land."
Justin Timberlake and Ant Clemons
Justin Timberlake and Ant Clemons delighted fans with their duo of Better Days during the Celebrating America TV special. The song was performed with a full band, led by Emmy-nominated musical director Adam Blackstone, in the Stax Museum of American Soul Music, before the two men stepped outside to finish it off in the streets.
The pair also invited students and alumni of Stax Music Academy to perform alongside them.
'Feeling Good', 'Lovely Day' and 'Amazing Grace'
John Legend, who helped the new president and vice president on their campaign trail last year, performed a stunning and soulful rendition of Nina Simone's Feeling Good. He did so while seated at a piano at the steps of the Lincoln Memorial.
Meanwhile, Demi Lovato belted out Lovely Day from Los Angeles as part of the TV special. The singer, 28, donning a beige power suit, incorporated famous and important faces in her performance, including Broadway star Lin-Manuel Miranda and a number of health and essential workers.
Country star Garth Brooks also tugged at the heartstrings when he led a singalong of Amazing Grace.
Katy Perry's 'Firework'
As the final performer of the Celebrating America concert, Perry pulled out all the stops. Decked in an elegant outfit by Thom Browne, with hints of red, white and blue, she performed her smash hit Firework as pyrotechnics lit up the Capitol.
The Grammy-nominated pop star sang in front of the Lincoln Memorial Reflecting Pool, as the president and his wife, and the vice president and her husband, watched.
Goldwyn and Stewart
As the traditional inauguration parade was not an option because of the ongoing coronavirus pandemic, a virtual live-streamed version was held, led by Scandal star Tony Goldwyn and Jon Stewart.
"Although as individual citizens we have our differences, more in some moments than others, one bond that unites us as Americans, especially today, is our belief in our enduring democracy," said Goldwyn, who played President Fitzgerald Grant for seven seasons on the ABC show, as he guided the audience through the presidential escort from an off-site studio space.
Stewart, who appeared via video against a backdrop of trees to kick--off the parade, said: "It's been a tough year – a pandemic, economic downturn, political division, social unrest – but we need to remember this ... there are millions of unsung American heroes who are keeping our nation going, caring for our loved ones, teaching our kids, keeping us all connected, making us smile, reminding us about what it is to truly be an American and what is great about America. That's what this day is about, an America united by our commitment to each other."
According to the Presidential Inaugural Committee, the virtual parade included 1,391 participants, 95 horses and nine dogs.
A band reunited for Beau
A range of performances were held for the parade, including one by the New Radicals, who haven't played together in 22 years. Reuniting for the one-time performance, the band delivered their 1998 hit song You Get What You Give.
The song holds particular poignance for the Biden family, as Joe revealed in his 2017 autobiography, Promise Me, Dad, that it was their rallying song throughout his late son Beau's battle with cancer.
"Performing the song again after such a long time is a huge honour because we all have deep respect for Beau’s military service and such high hopes for the unity and normalcy Joe and Kamala will bring our country again in this time of crisis," said New Radicals frontman Gregg Alexander.
The band had made a pledge last year, saying: "If Joe won, we'd get together and play our little song." And they certainly made good on that promise.
Earth, Wind & Fire meets Sister Sledge
It's been more than 50 years since Earth, Wind & Fire formed, but the members of the band came back together last night for the parade. They joined DJ Cassidy, as he dedicated the performance to "amazing Americans".
Following a rendition of Sing a Song, Kathy Sledge of Sister Sledge joined the group to belt out We Are Family, as images of all-American families were projected on to the audience's screens.
An epic nationwide dance-off
A Dance Across America segment finished off the parade, featuring 275 participants from 30 states dancing in landmark spots across the country, all led by director and choreographer Kenny Ortega.