Trump has repeatedly attempted to question the validity of vote counts in key swing states and made unfounded claims that the election is being "stolen" from him.
The 77-year-old former US vice president will become the 46th president of the United States, CNN reported, after a victory in Pennsylvania, the state where he was born put him over the 270 electoral votes needed to win.
Major American media outlets started calling Biden the winner after it became clear that he has taken a major lead against Republican incumbent Donald Trump in the battleground State of Pennsylvania, which has 20 electoral college votes, making him cross the benchmark of the 270 electoral college votes.
Twitter immediately flagged Trump's tweet saying that "official sources may not have called the race when this was tweeted.
'We may be opponents - but we are not enemies. We are America'
The Trump campaign has alleged that a significant number of mail-in ballots arrived after the 8 pm deadline of closing of polls on November 3.
Biden also announced that he will introduce his plans to contain the COVID-19 pandemic on his first day in office.
As per the latest projections, Biden has 253 electoral college votes and Trump trails behind with 213. But some US media outlets have given 264 votes to Biden and 214 to Trump.
Trump has challenged the authenticity of the elections, alleging massive voters fraud and electoral malpractice. In another tweet, he said his leads in all of these states were significant on election night but suddenly started vanishing. He asserted that the lead would come back once the legal proceedings move forward.
'We believe the American people deserve to have full transparency into all vote counting and election certification, and that this is no longer about any single election. 'This is about the integrity of our entire election process,' Trump said in a statement issued by his campaign on Friday.
Even as the election was yet to be called in Pennsylvania and Georgia where Biden has taken over Trump in terms of the vote count, albeit by a thin margin, the window for Trump was fast closing down.
Biden -- who bagged 253 seats as against Trump's 213 -- appeared to be nearing the magical figure of 270 of the 538 electoral college votes.
The US president mentioned that there was no "big blue wave" (Democrats) as pollsters had predicted, instead, there was a "big red wave" (Republicans).
The November 3 election saw a record voter turnout of 66.9 per cent, which is the highest turnout rate since 1900. The 1900 election had recorded 73.7 per cent voter turnout
Biden also urged Americans to stay calm and wait patiently while every vote is being counted. Biden is just shy of reaching the magic figure of 270 and win the race to the White House.
In Michigan, the campaign had sought to stop counting of absentee ballots, while in Georgia it had alleged that even improper ballots were being counted. In Georgia, Judge James F Bass dismissed the lawsuit.
Nevada is the fourth State where the Trump Campaign has filed a lawsuit. United States President Donald Trump, who has 214 votes so far, has filed lawsuits in Pennsylvania, Georgia, Michigan and demanded recounting of votes in Wisconsin.
'Big legal win in Pennsylvania,' Trump said in a tweet soon after the court gave the ruling. Trump is currently leading in Pennsylvania, but his vote count has reduced considerably over the last one day.
As per projections made by major media outlets, Biden has 264 electoral college votes, just six votes short of the magical number of 270 out of 538 required to win the presidency. However, for news outlets like CNN, Biden has 253 electoral college votes as it has still not called Arizona, which has 11 votes and counting of votes continued.
More than eight million young people who voted early or absentee in the 2020 elections.