The fortified hamlet Fosdinovo fought long time against the powerful count-bishops of Luni, to finally give up in XII century. Following the peace mediated by Dante Alighieri (beginning of XIV century), the bishops retreated from Fosdinovo again, and the town fell under the rule of Castruccio Castracani, and then of the Malaspina family. Spinetta was the first Malaspina master, opening a five-century period in which Fosdinovo's castle is enlarged and strengthened, to finally become what now is: an extraordinary example of medieval architecture.

Under the Malaspinas Fosdinovo knew a period of peace and prosperity that lasted until the French Revolution. In 1666 Fosdinovo was granted by the imperial authority the right to mint coins; in this period, the only two other towns in the Valle benefiting from this special privilege are Massa and Tresana.

After the Vienna Congress, the territories once dominated by the Malaspina were annexed to the Estensi possessions, and thus became part of the Granducato di Ferrara ("Ferrara grand duchy"). The new masters acknowledged Fosdinovo importance, and the town became chief town of the Lunigiana district. During the second half of XIX century the Granducato di Ferrara became part of the Regno d'Italia ("Italy Kingdom", till World War II), and so did Fosdinovo.