The court in the northern city of Thessaloniki ruled in favor of France's request for Alexander Vinnik, a former bitcoin operator who was arrested in Greece last year on a U.S.-issued international warrant.
Vinnik is appealing the decision, defense lawyer Ilias Spyrliadis said.
France is seeking the 38-year-old for alleged cybercrime, money laundering, membership in a criminal organization and extortion. The Greek Supreme Court earlier approved Vinnik's extradition to the U.S. to stand trial for allegedly laundering billions of dollars using bitcoin.
French authorities accuse Vinnik of defrauding thousands of people worldwide, including about 100 French nationals, by launching cyberattacks through his bitcoin platform. They allege he used 20,643 bitcoins to launder around 133 million euros ($155 million.)
Vinnik has denied doing anything illegal. He remains jailed in Greece pending final decisions on his extradition.
Meanwhile, Russian authorities sent a new request this month for Vinnik's extradition Russia initially sought Vinnik on lesser fraud charges, and a Greek court ruled for his extradition to Russia based on the first request. The second request raises the amount of money allegedly involved in the cyberfraud there to 750 million rubles ($12 million.)
Spyrliadis said a European warrant ordinarily would take precedence over others, giving France first dibs on prosecuting Vinnik. But he said in practice, it'll be up to Greece's justice minister to decide where Vinnik ends up.