Mr Biden was declared the “apparent winner” of the US election by a key federal agency, clearing the way for the start of the transition.
President Trump, who had refused to concede the election, said he was directing his team to co-operate on the transition but vowed to keep up the fight.
A federal official said the determination was made after Mr Trump's efforts to subvert the vote failed across battleground states, most recently in Michigan.
The move clears the way for Mr Biden’s aides to begin co-ordinating with federal agencies on plans for the takeover on January 20.
"Please know that I came to my decision independently, based on the law and available facts," Emily Murphy of the General Services Administration (GSA) wrote in a letter to Mr Biden.
"I was never directly or indirectly pressured by any executive branch official - including those who work at the White House or GSA - with regard to the substance or timing of my decision."
Mr Trump tweeted shortly after her letter was made public: "Our case STRONGLY continues, we will keep up the good... fight, and I believe we will prevail!
"Nevertheless, in the best interest of our Country, I am recommending that Emily and her team do what needs to be done with regard to initial protocols, and have told my team to do the same."
It comes after Mr Biden’s election victory the US state of Michigan has been officially certified, in a huge blow to Mr Trump’s attempts to challenge the result.
The Board of State Canvassers, which has two Republicans and two Democrats, confirmed the results on a 3-0 vote with one abstention.
Mr Trump claimed voter fraud swayed the outcome of the vote. He did not offer evidence. His 's Republican allies had called for the certification to be delayed to audit ballots in heavily Democratic Wayne County, home to Detroit.
But election officials on Monday night certified Democrat Mr Biden's 154,000-vote victory. With the results now certified, Mr Biden has won by a 2.8 per cent margin and will receive all 16 of the state's electoral college votes.
"The people of Michigan have spoken,” Michigan Governor Gretchen Whitmer, a Democrat, said, adding that it is "time to put this election behind us."
Mr Trump’s legal team dismissed the certification as "simply a procedural step" and insisted it would fight on.