The BBC projected Mr Biden’s victory on Saturday after gains in the key battlegrounds of Pennsylvania and Nevada propelled him over the 270 electoral college vote threshold required to clinch the White House.
Mr Trump has not spoken in public since the numbers were announced, but he has repeated previous claims of voter fraud in tweets, which Twitter soon marked as a “disputed” claim. The Trump campaign has indicated their candidate does not plan to concede.
After Mr Biden was projected to win Mr Trump remained defiant, saying Mr Biden was “falsely posing as the winner” and insisting the election was “far from over”. The president took more than 70 million votes, the second-highest tally in history.
What happens now
Mr Trump has vowed to contest the election results on several fronts. A recount will be held in Georgia, where the margins are tight, and Mr Trump wants the same in Wisconsin. He has also vowed to take legal action to the Supreme Court, alleging voting fraud without evidence.
If the election result is challenged, it would require legal teams to challenge this in the state courts. State judges would then need to uphold the challenge and order a recount, and Supreme Court justices could then be asked to overturn a ruling.
On Saturday, the Trump campaign filed a lawsuit over ballots cast on election day in Arizona that it claims were incorrectly rejected. Arizona’s secretary of state, however, said in a statement that the case was “grasping at straws”.
Meanwhile, votes in some states are continuing to be counted and results are never official until final certification, which occurs in each state in the weeks following the election.
This must be done before 538 chosen officials (electors) from the Electoral College – which officially decides who wins the election – meet in their state capitals to vote on 14 December.
The electors’ votes usually mirror the popular vote in each state. However, in some states, this is not a formal requirement.
The new president is officially sworn into office on 20 January after a transition period to give them time to appoint cabinet ministers and make plans.
The handover of power takes place at a ceremony known as the inauguration, which is held on the steps of the Capitol building in Washington DC. After the ceremony, the new president makes their way to the White House to begin their four-year term in office.