Investigators say the data centre had hosted online sites dealing drugs and other criminal businesses.
Eight people have been convicted in Germany for operating an illegal data processing centre at a former military bunker.
The data centre - located in western Germany - was used to host sites dealing drugs and other illegal activities.
It was shut down after German authorities raided the site in the town of Traben-Trarbach in September 2019.
Investigators had described the data computer centre as a "bulletproof hoster" meant to conceal illicit activities from the authorities.
The state court in nearby Trier convicted all eight defendants of forming and being a member of a criminal organisation.
However, they were acquitted of being accessories to some 250,000 crimes that were allegedly committed via the websites hosted by the data centre.
The ruling handed down by presiding judge Gunther Köhler marked the end of the year-long so-called Cyberbunker trial.
The main suspect was sentenced to five years and nine months in prison, while the other defendants were handed punishments ranging from four years and three months in prison to a one-year suspended sentence.