Bosnia's war crimes court found Branko Vlaco, 61, guilty of setting up and running four "detention centres" in the Sarajevo suburb of Vogosca from May to October 1992, where Muslim and Croat civilians were illegally held.
"Vlaco took part in expulsions and executions of civilians," judge Minka Kreho said while reading the verdict.
The verdict described in details the deaths of numerous detainees taken to the frontlines as "human shields" or tortured in detention centres.
According to victims' associations, some 800 civilians were detained in the Serb-run camps in Vogosca.
An estimated 300 of them were killed, while some 60 people are still considered missing.
Bosnia's 1992-1995 inter-ethnic war claimed some 100,000 lives. More than 9,000 people are still missing, official data shows.