The UK's Supreme Court says the bid did not "raise an arguable point of law."
Julian Assange is facing espionage charges and an 18-count indictment.
WikiLeaks founder Julian Assange's attempt to appeal extradition was denied by the UK's Supreme Court on Monday. Assange was initially granted the right to petition the court in late January.
The UK's highest court denied Assange's bid because "the application does not raise an arguable point of law," according to a statement released by the court.
Assange faces espionage charges relating to WikiLeaks' release of confidential US military records about the wars in Iraq and Afghanistan. Assange could potentially face a 175-year jail sentence, though US officials said, if he's convicted, his sentence would likely be between four and six years.
Interior Minister Priti Patel must now ratify the extradition decision, which Assange can then challenge via judicial review, according to Reuters.
"Mr. Assange will continue the legal process fighting his extradition to the United States to face criminal charges for publishing truthful and newsworthy information," Barry Pollack, Assange's US-based lawyer, said Monday.