"The Court of Cassation dismisses the appeals ... considering that the reasons adopted by the judges, which are part of their assessment, are sufficient," France's highest appeals court said in a statement as it upheld the ruling.
The League party of Italian Deputy Prime Minister Matteo Salvini described the decision as "disconcerting".
Italy has long sought the extradition of the former guerrillas, who were given refuge in France on condition they renounced violence following the so-called "Years of Lead" of left and right-wing terrorism from the late 1960s to the 1980s.
In April 2021, France arrested seven former Italian leftist militants after harbouring them for decades following their conviction in Italy on terrorism charges.
The group concerned by Tuesday's decision consisted of those seven people and three more, all aged between 62 and 89.
Last year, a decision by a lower court not to extradite them on grounds of their human rights, had sparked a rift between Rome and Paris, with some Italian politicians accusing French judges of taking an "unacceptable" decision.
Giorgia Meloni, the leader of the far-right Brothers of Italy party who later became the country's prime minister, last summer called it "unacceptable and shameful" not to deport the militants.
Amongst those concerned by Tuesday's ruling was Giorgio Pietrostefani, a co-founder of the Lotta Continua (Continuous Struggle) group, sentenced to 22 years in prison for his role in the 1972 murder of Milan police commissioner Luigi Calabresi.
Members of the Red Brigades, including Marina Petrella, Roberta Cappelli and Sergio Tornaghi, all sentenced to life in prison for taking part in various murders and kidnappings, are also among those who have avoided extradition.
(Reporting by Tassilo Hummel, Marine Strauss; additional reporting by Alvise Armellini; Editing by GV De Clercq and Christina Fincher)
