Assange, 39, is wanted by Swedish authorities, who have accused him of one count of unlawful coercion, two counts of sexual molestation, and one count of rape for incidents that allegedly occurred in August.
Assange was scheduled to appear at City of Westminster Magistrates Court in London later Tuesday. He had been the subject of an Interpol "red notice" that asked member countries to arrest and detain him for extradition to Sweden.
The charges, which Assange has denied, may be just the beginning of the Australia native's legal troubles.
U.S. authorities have suggested he could face espionage charges for publishing classified documents that divulged the innermost workings of American diplomacy.
The leaked documents revealed serious concerns within the U.S. diplomatic community about the resolve and trustworthiness of several key allies, including Afghanistan and Pakistan, in the war on terror. They also disclosed Saudi Arabia's wish for a U.S. military strike against Iran, and painted unflattering pictures of Western leaders like German Chancellor Angela Merkel and Italian Prime Minister Silvio Berlusconi.
Excerpts of the documents were published by several major newspapers, including The New York Times, The Guardian, Der Spiegel, and Le Monde, after they obtained them from WikiLeaks.
Despite Assange's arrest, WikiLeaks is vowing to continue publishing classified U.S. documents.
"WikiLeaks is operational. We are continuing on the same track as laid out before," a spokesman for the group said. "Any development with regards to Julian Assange will not change the plans we have with regards to the releases today and in the coming days," said the spokesperson, according to Reuters.
WikiLeaks has shifted operations internationally several times in the past couple of weeks after it was booted by its U.S.-based hosting company, Amazon Web Services, for violating a terms of service agreement.