A judge in Palermo, Sicily, convicted them for protecting Provenzano while he was in hiding.
Others were implicated in managing Mafia funds.
Provenzano, 73, spent four decades on the run before being arrested in April at an isolated farm near Corleone, close to Palermo.
Among the 57 convicted people, one group is said to have organised for Provenzano to travel to southern France to receive cancer treatment under an assumed identity.
Nicola Mandala, who was accused of planning the trip, was sentenced to more than 13 years in prison.
The longest jail sentences of 18 years were given to Benedetto Spera, a Mafia boss who controlled a region near Palermo, and Onofrio Morreale.
The trial was a fast-track one, whereby sentences are reduced when defendants enter a guilty plea. [From the BBC]