The 47-year-old is currently in custody in the UK. He was jailed for 50 weeks for breaching his bail after spending seven years in the Ecuadorian Embassy to avoid extradition to Sweden over a rape allegation.
He is also wanted in the US on a number of charges, including espionage and computer hacking.
Assange told the court that "175 years of my life is effectively at stake" and argued that WikiLeaks is "nothing but a publisher".
"I want to see justice done at all times and we've got a legitimate extradition request, so I've signed it, but the final decision is now with the courts," Javid said on Thursday.
Ben Brandon, on behalf of US justice, said that the case "is related to one of the largest commitments of confidential information in the history of the US".
Mark Summers, representing Assange, said that the allegations represent "an outrageous and full-frontal assault on journalistic rights".
A crowd of protesters gathered outside the court in central London holding banners of support.
Assange came to international attention in 2010 after WikiLeaks published leaked military information provided by former US soldier Chelsea Manning, which prompted its government to launch a criminal investigation into the publisher.
In November that year, Sweden requested his extradition over allegations of sexual assault and rape, which he denied. Assange also expressed concern that he would be extradited from Sweden to the US because of his role in the Manning leaks. He surrendered himself to the UK police around a month later and was held in custody for 10 days before being released on bail.
When he was unable to challenge the extradition proceedings, he breached bail and in August 2012 was granted asylum by Ecuador. He remained sheltered in the country's London Embassy for seven years to avoid arrest.
Sweden has reopened its investigation into the allegations of rape and sexual assault.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)