The British former One Direction star, 26, shared a campaign video from the Democratic contender on Twitter. He wrote: “If I could vote in America, I’d vote with kindness.”
Biden’s campaign video showed the politician and former vice-president under Barack Obama, 77, meeting voters in the lead-up to election day.
It was captioned: “You deserve a president who will get up every single day and work to make your life better. If you elect me, that’s exactly what I’ll do.”
British singer and actor Styles, who is not eligible to vote in the forthcoming election, follows in the footsteps of stars including Justin Timberlake and Taylor Swift in backing Biden.
Mel Brooks, Dwayne “The Rock” Johnson and Jennifer Lopez are also among those supporting the Democrat’s White House bid.
Styles previously addressed President Donald Trump’s politics during an appearance on James Corden’s Late Late Show in 2017.
He joked: “Of course, the big story of tonight is that Donald Trump shared secret information with the Russians last week.
“The good news for Trump is that he has been named employee of the month by Russia.”
Catwalk star Bella Hadid also shared a political message, encouraging her 34.8 million Instagram followers to vote.
The 24-year-old posed next to a piece of street art which said: “Voting is a super power, use it don’t lose it”, while wearing a black and red tracksuit with matching face mask.
Styles has recently released Golden – the fifth single from his second solo album, Fine Line.
The video for the single was watched over 15 million times in 24 hours and was the number one trending video on YouTube.