The High Court in London ruled in his favour observing that Assange's case raised a question "of general public importance" which should be decided by the highest court in the land "as quickly as possible".
Swedish authorities want to question the Australian founder of the whistle-blowing website over accusations of rape and sexual assault made by two female former WikiLeaks volunteers during a visit there in August 2010.
40-year-old Assange, who has been living in Britain since his arrest here in December last year, denies wrongdoing.
Assange claims the allegations are politically motivated and linked to the activities of his anti-secrecy website, which angered the United States by publishing thousands of classified documents last year.
Had today's decision gone against him, Assange would have faced extradition within 10 days.
He had spent nine days in London's Wandsworth prison after his arrest last year. He was freed a week before Christmas on bail and has since been living at the country house of a wealthy supporter in eastern England.
Last year, WikiLeaks posted 391,832 secret papers on the Iraq war and 77,000 classified Pentagon documents on the Afghan conflict.
It has also made available about 250,000 individual cables, daily traffic between the State Department and more than 270 American diplomatic outposts around the world.