The Home Secretary revealed on BBC Radio 4 that he had "signed and certified" the extradition order in advance of a court hearing in London tomorrow when it is expected the United States will detail all the charges against the Wikileaks founder.
He is accused of conspiring with former US Army intelligence analyst Chelsea Manning to crack passwords to gain access to the information, which was subsequently posted on WikiLeaks.
"There's an extradition request from the USA that is before the courts tomorrow, but yesterday I signed the extradition order, certified it, and that will be going in front of the courts tomorrow", Javid said according to Australia's public broadcaster, the ABC.
Although Javid has officially signed the extradition order, it is only the first step in what could prove to be a lengthy legal battle over whether Assange should face prosecution in the US.
Sweden has also reopened its own investigation into a 2010 rape allegation made against the WikiLeaks founder.
The WikiLeaks founder is due to appear via video link before Westminster Magistrates' Court on Friday for a case management hearing after the U.S. requested his extradition.
Extradition lawyer Thomas Garner, from Gherson Solicitors, said today: 'I would expect the court to set a preliminary timetable for the extradition process tomorrow.
Assange's initial indictment sparked a debate over the First Amendment and whether his alleged role in procuring secret USA material constituted protected journalistic activity.
The ruling doesn't mean Sweden preliminary rape investigation will be abandoned, only that Assange won't be extradited to Sweden for now. "I want to see justice done and we have a legitimate extradition request". Javid is Muslim, though he insists he doesn't know why he wasn't invited to the recent USA -focused events in Britain.
Mr. Assange, who faces an 18-count indictment by the U.S. Justice Department, was too ill to appear before Westminster Magistrates' Court at a scheduled hearing last month and his next hearing is expected to take place at the high-security Belmarsh jail in London, where he is being held.
The secretary then decides whether to order an extradition. It is nearly certain Assange will file an appeal to the High Court after the district judge's ruling, and again (as the law allows) after the Home Secretary's final decision.