The General Services Administration's announcement on Monday that it would formally recognize Biden's transition came after weeks of the president falsely claiming that the Nov. 3 election had been marred by widespread voter fraud.
Trump, in a post on Twitter, offered support for the move.
Critics have said the president's refusal to accept the results undermined U.S. democracy and undercut the next administration's ability to fight the novel coronavirus.
While Trump stopped short of conceding, it was the closest he has come to acknowledging that it is time to hand over power to Biden, who will take office on Jan. 20.
The GSA announcement will allow the president-elect to access millions of dollars in funds and focus on putting together a leadership team.
It also paves the way for Biden and Vice President-elect Kamala Harris to receive regular national security briefings that Trump also gets.
On Tuesday, Biden and Harris are expected to formally introduce their appointments to critical national security and foreign policy positions in Wilmington, Delaware.
Two Trump administration officials said the Biden agency review teams could begin interacting with Trump agency officials as soon as Tuesday.
The Biden transition team said meetings would begin with federal officials on Washington's response to the coronavirus pandemic, along with discussions of national security issues.
Biden on Monday tapped trusted aide Antony Blinken to head the State Department and John Kerry, a former U.S. senator, secretary of state and 2004 Democratic presidential nominee, to serve as his special climate envoy.
Biden, who plans to undo many of Trump's "America First" policies, also named Jake Sullivan as his national security adviser and Linda Thomas-Greenfield as U.S. ambassador to the United Nations — both with high-level government experience.
He is likely to tap former Federal Reserve Chair Janet Yellen to become the next Treasury secretary, according to two Biden allies, who spoke on condition of anonymity to discuss a personnel decision that was not yet public.
On Monday evening, Sue Gough, a spokeswoman for the Pentagon, said that the Department of Defense had been contacted by the Biden-Harris team.
"DoD is prepared to provide post-election services and support in a professional, orderly, and efficient manner that is befitting of the public’s expectation of the Department and our commitment to national security," Gough said.
While Trump on Monday said he backed GSA Administrator Emily Murphy's decision, he and his advisers vowed to continue fighting the election results.
"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," Trump said on Twitter.
...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.— Donald J. Trump (@realDonaldTrump) November 23, 2020
Trump later said on Twitter that his team would move "full speed ahead" with challenging "what will go down as the most corrupt election in American political history," adding that he would "never concede."
What does GSA being allowed to preliminarily work with the Dems have to do with continuing to pursue our various cases on what will go down as the most corrupt election in American political history? We are moving full speed ahead. Will never concede to fake ballots & “Dominion”.— Donald J. Trump (@realDonaldTrump) November 24, 2020
Biden won 306 state-by-state electoral votes to Trump’s 232. Biden also holds a lead of more than 6 million in the national popular vote.
Murphy's decision to allow the formal transition followed weeks of failed legal efforts by Trump and his allies to overturn the election in key battleground states.
Murphy, who was appointed to the GSA job by Trump, said she faced threats for not starting the transition earlier and told GSA employees in a letter that the decision to do so was hers alone.
The letter came shortly after Michigan officials certified Biden as the victor in their state.
Nevada Secretary of State Barbara Cegavske, a Republican, is due to meet with state supreme court justices on Tuesday to certify that state's vote. Biden won Nevada by more than 33,000 votes, according to the Nevada secretary of state's office.
Representative Don Beyer, who led the Obama administration's transition at the Commerce Department in 2008, said on Monday that Murphy's delay was "costly and unnecessary" and warned that Trump could still do great harm in his remaining time in office.
(Reporting by Trevor Hunnicutt, Jess Mason, Andrea Shalal, David Shepardson, Michael Martina, James Oliphant, Julia Harte, Patricia Zengerle, Susan Heavey, Richard Cowan and David Morgan; Writing by Noeleen Walder Editing by Robert Birsel)