Biden became the 46th president of the United States after taking the oath of office on the West Front of the U.S. Capitol.
Harris has become the first woman and first woman of color in U.S. history to be sworn in as vice president.
"I was at work, but apparently she said: 'Is that mommy? It looks like mommy.' Best compliment I ever got! It matters. Happy Inauguration everyone," Kaling said on Instagram, alongside an image of her three-year-old daughter Katherine watching Harris on a television screen.
"Just wanna let you know. It's never too late to chase your dreams. Joe Biden in 78 and is becoming the president of the United States today. Don't give up," Rexha said on Twitter.
"Hey Everybody, today we're ALLLL good! God bless you REAL good @joebiden & @kamalaharris ! Our country in your hands is a great good thing! Amen, Amen, and AMEN! #inauguration #theywalkeduptheweststeps #sayitagain," Angela Bassett said on Instagram, alongside a photo of the U.S. Capitol.
"Today, we make history! Today, we celebrate leaders like President @joebiden and our first Madam Vice President, @kamalaharris. Today is only the beginning," Longoria said on Instagram, alongside a photo of herself with Biden.