Of probable Lombard origin, they appear in history as the counts of Santa Fiora in the late 8th and early 9th centuries, although a Ghidelmo Aldobrandeschi is mentioned as lord of Roselle as early as 729. The possession extended to what are now southern Tuscany and northern Lazio regions of Italy.
In 1274, their lands were divided between the County of Santa Fiora and the County of Sovana, which thenceforth were ruled by different branches of the family. After the extinction of the Aldobrandeschi of Sovana, the county was assigned to the Orsini. The Aldobrandeschi heiress of Santa Fiora married into the Sforza family.
The most famous members were Guglielmo Aldobrandeschi, who lived in the 13th century and is cited by Dante Alighieri as the Gran Tosco (“Grand Tuscan”), and Pope Gregory VII.