The court panel "found the accused Xhemshit Krasniqi guilty of committing the criminal offence of war crimes against the civilian population," the EU rule of law mission (EULEX) said in the statement.
Krasniqi was a member of the Kosovo Liberation Army (KLA) that fought security forces loyal to the then Serbian strongman Slobodan Milosevic.
Krasniqi "was found guilty of arrest, illegal detention, violation of bodily integrity, health and torture of several witnesses and unknown civilians in the KLA camps" in Albania and Kosovo, EULEX said.
Just months after Kosovo unilaterally declared independence from Serbia in 2008, the EU launched a large civilian mission to help the young country improve its rule of law.
EULEX's mostly European judges and prosecutors can take over court cases that the local judiciary cannot handle due to their sensitivity.