The British High Court is set to announce at 0945 GMT whether the 40-year-old Australian, whose whistle blowing website has enraged governments around the world, should be extradited to Sweden, following his arrest in December.
A lower court ruled in February that Assange should be sent to face questioning by Swedish authorities over claims of sexual assault against two women, triggering a lengthy and bitter appeal battle.
The enigmatic WikiLeaks boss has been living under strict bail conditions, including having to wear an electronic ankle tag and observe a strict dusk-to-dawn curfew, at the east-England mansion of supporter and former army captain Vaughan Smith.
The long-awaited decision, which has been deferred since the High Court heard Assange's appeal in July, may not be the final chapter in the saga, but it will be difficult for either side to lodge an appeal.
Depending on the verdict, either Assange or the Swedish authorities can theoretically take the case a step further to the Supreme Court in London, the highest legal authority in the land.
"If you fulfill certain criteria you may get permission to appeal to the Supreme Court," a spokeswoman for the office of the Judiciary of England and Wales told AFP.
But leave to appeal can only be granted by either the High Court or the Supreme Court, and then only if it there is a point of law of general public importance.
Assange denies the allegations and claims they are politically motivated.
The former hacker caught the world's attention when WikiLeaks released tens of thousands of classified diplomatic files allegedly obtained by a US serviceman who is now in prison in the United States.
But Assange also achieved a different kind of notoriety when the allegations of sexual assault were made against him by two Swedish women in August 2010.
In July's hearing, lawyers representing Swedish prosecutors rejected claims that a rape allegation against Assange, made by one of the women, would not be valid under English law.
Swedish lawyers accused Assange's legal team of "winding English law back to the 19th century" with their definition of consent.
Assange's lawyers have also claimed that the European warrant under which he was arrested was invalid because he is only wanted for questioning and has not been charged by Swedish authorities.
In an autobiography published in September, Assange repeated his denial of the rape allegations.
"I did not rape those women and cannot imagine anything that happened between us that would make them think so, except malice after the fact, a joint plan to entrap me, or a terrifying misunderstanding that was stoked up between them," he wrote.
"I may be a chauvinistic pig of some sort but I am no rapist, and only a distorted version of sexual politics could attempt to turn me into one."