Jari Aarnio was found to have helped a gang to import nearly 800kg (1,764lb) of hashish from the Netherlands and sell it in Finland in 2011-2012.
Aarnio, 59, was found guilty of five drug crimes and 17 other offences.
These included trying to frame an innocent man for being in charge of the drug ring.
An accomplice of the former senior policeman, described as a top local criminal, was also sentenced to 10 years in prison.
Aarnio spent 30 years in the anti-drugs force and was arrested in 2013.