It is located on the extreme slopes of the Pratomagno massif, at the point where it moves towards the plain of Arezzo, along the ancient Via Clodia (or Cassia Vetus), the main road that connects Arezzo to Loro Ciuffenna.
The small fraction of Gello Biscardo with its splendidly preserved ancient village also belongs to the municipal territory of Castiglion Fibocchi.
The first settlements were probably in the imperial era; in the early Middle Ages a parish church “Plebs S. Quirini supra Aurum” and six suffragan churches were established.
Its name was "Castrum Leonis de Filiis Bocchi", later reduced to "Castrum de Filiis Bocchi".
Around the year one thousand the area became the property of the Guidi Counts who provided it with a castle to control the road that connected the Valdarno to the Casentino. Later it was given to Ottaviano dei Pazzi del Valdarno.
In 1384 Arezzo and its countryside passed to the Florentine Republic, being enfeoffed in the grand-ducal era as a marquisate to Alessandro del Borro. It was then inserted in the Laterina podesteria.
At the beginning of the 18th century the property of Castiglion Fibocchi was inherited by the Dukes of Lorraine, who abolished feudalism and elevated the village to the rank of an independent municipality, detaching it from the community of the "Two District Municipalities of Laterina".
In 1835, with the victory of the city of Florence over Arezzo, Castiglion Fibocchi was also incorporated into the territory of the Republic of Florence.
In 1860, at the plebiscite organized for the annexation of Tuscany to Sardinia, Castiglion Fibocchi expressed himself with an overwhelming majority in favor of maintaining the separate kingdom (out of 293 having rights, 169 voters, the separate kingdom had 106 votes against 46 which went to the annexation and 17 void). Hence the title of "King of Castiglion Fibocchi" given to Ferdinand IV of Tuscany, who succeeded the last reigning sovereign of Tuscany, Leopold II of Tuscany.