Delegates from around the country cast votes remotely to confirm Mr Biden as the nominee on Tuesday.
It comes as party officials and activists from across the nation gave the former vice president their overwhelming support during his party’s all-virtual national convention.
The moment marked a political high point for Mr Biden, who had sought the presidency twice before and is now cemented as the embodiment of Democrats’ goal to defeat Donald Trump this autumn.
The roll call of convention delegates formalised what has been clear for months since Mr Biden took the lead in the primary elections’ chase for the nomination.
Former Democratic presidents Jimmy Carter and Bill Clinton endorsed Mr Biden during the second night of the Democratic National Convention which is being held online due to the coronavirus outbreak.
Two former Democratic presidents, Jimmy Carter and Bill Clinton, offered their endorsements of Mr Biden.
Mr Clinton condemned Mr Trump's leadership during the pandemic saying: “Covid hit us much harder than it had to".
In comparison Mr Clinton praised Mr Biden as a "go-to-work president".
“Our party is united in offering you a very different choice: a go-to-work president," he said.
"A down-to-earth, get-the-job-done guy. A man with a mission: to take responsibility, not shift the blame; concentrate, not distract; unite, not divide.”
Tuesday's programme featured17 stars in a video address, including Stacey Abrams, whom Mr Biden once considered for a running mate.
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She said: “America faces a triple threat: a public health catastrophe, and economic collapse and a reckoning with racial justice and inequality.
"So our choice is clear: a steady experienced public servant who can lead us out of this crisis just like he’s done before, or a man who only knows how to deny and distract.”
Jill Biden addressed the nation for the first time as the prospective First Lady, offering a deeply personal portrait of her husband of more than 40 years.
A longtime teacher, she was speaking from her former classroom at Brandywine High School near the family home in Wilmington, Delaware. She reflected on the devastating death of Biden's son, Beau, who died of cancer in 2015.
"There are times when I couldn't imagine how he did it — how he put one foot in front of the other and kept going," Mrs Biden said. "But I've always understood why he did it. He does it for you."
It comes after former First Lady Michelle Obama offered a sharp rebuke of the Trump presidency during the first evening of the Democratic National Convention.
She told viewers Mr Trump “has had more than enough time to prove that he can do the job, but he is clearly in over his head”.
“He cannot meet this moment,” she added. "If you think things cannot possibly get worse, trust me, they can”.
Mr Biden will formally accept the Democratic presidential nomination inside a mostly empty Delaware convention hall on Thursday.
His running mate, California Senator Kamala Harris, will become the first woman of colour to accept a major party's vice presidential nomination on Wednesday.
Until then, Mr Biden is presenting what he sees as the best of his coalition to the American electorate in a format unlike any other in history. There is no live audience for any of the speakers, who have so far delivered their remarks standing or seated alone in mostly prerecorded videos.
Additional reporting by Associated Press.