According to a short note released by London's Metropolitan Police Service, Assange was arrested immediately after the Ecuadorian government today withdraws his political asylum.
Assange has now been taken into custody at a central London police station, from where he will be presented before Westminster Magistrates' Court as soon as possible.
U.S. Department of Justice also confirmed today that Assange would face extradition proceedings for his alleged role in "one of the largest compromises of classified information in the history of the United States."
"The indictment [unsealed today] alleges that in March 2010, Assange engaged in a conspiracy with Chelsea Manning, a former intelligence analyst in the U.S. Army, to assist Manning in cracking a password stored on U.S. Department of Defense computers connected to the Secret Internet Protocol Network (SIPRNet), a U.S. government network used for classified documents and communications."
Following his arrest on Thursday, Ecuadorian President Lenín Moreno tweeted, "In a sovereign decision, Ecuador withdrew the asylum status to Julian Assange after his repeated violations to international conventions and daily-life protocols."
However, WikiLeaks said Ecuador had acted illegally in terminating Mr Assange's political asylum "in violation of international law."
Assange's arrest comes a day after WikiLeaks editor Kristinn Hrafnsson accused the Ecuadorian government of an extensive spying operation against Julian Assange inside the Ecuadorian embassy.
Assange was wanted by British police for failing to surrender to the Westminster Magistrates' Court in August 2012, while he was under investigation for sexual assault and rape allegations in Sweden.
In the United States, Assange is facing federal charges for leaking diplomatic cables and military documents through his popular publication WikiLeaks in 2010 that embarrassed the U.S. governments across the world.
Although U.S. authorities have never officially confirmed the charges against Assange, late last year U.S. prosecutors accidentally revealed the existence of criminal charges against him in a document filed in an unrelated sex crime case.
Assange, the 47-year-old Australian hacker, founded WikiLeaks in 2006 and has since made many high-profile revelations through the platform, exposing 'dirty' secrets of several political parties, individuals, and government organizations across the world.
Assange has been forced to live in London's Ecuadorian Embassy since June 2012, when a U.K. court ordered his extradition to Sweden to face sexual assault and rape charges filed against him.
However, his relationship with Ecuador has deteriorated in the past year. The country had cut him off the Internet since March 2018 after he breached its agreement to refrain from interfering in other states' affairs that could affect the country's relationship with other nations.
The circumstances even made it difficult for Assange to do his job of editor-in-chief to run WikiLeaks and forced the whistleblower organization to appoint its new editor-in-chief, Kristinn Hrafnsson.
In July last year, the Ecuadorian President also reportedly visited London to finalize a deal with UK government to withdraw Assange's asylum protection—eventually turning him over to Britain where he is facing an arrest warrant after skipping a bail payment.