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Judge Michael Snow said he was satified that the European warrant under which the 55-year-old Spaniard was arrested in London last year complied with his human rights.
"I order his surrender to Spain," he told Westminster Magistrates Court in London.
Troitino's lawyers said they would appeal the extradition order. They have seven days to file the papers.
In the 1980s, Troitino was a member of ETA's Madrid unit, which carried out some of the separatist group's bloodiest attacks.
Spanish prosecutors say he set off the bomb in one of the unit's most notorious acts, a car bomb attack on a police bus in Madrid in July 1986 which killed 12 officers and wounded more than 50 others.
Troitino, also known as Antxon, was arrested in 1987 and sentenced to more than 2,700 years for 22 killings, even though the maximum stay in prison in Spain is 30 years.
A legal bungle in April 2011 set him free but before it was resolved, the Spaniard went on the run. He escaped to London, where he was arrested on June 29 last year.
Spanish prosecutors want him to serve the remainder of his 30-year-sentence, estimated at about six years.
ETA is blamed for more than 800 deaths in a four-decade campaign of bombings and shootings for independence for the Basque Country of northern Spain and southwestern France.