Morolo was settled around the year one thousand when the inhabitants of the river valleys sought refuge in fortresses on the heights, though definitely the site had been inhabited since the Volsci and then by the Romans.
The first official document mentions the Morolo castle as belonging to the diocese of Anagni.
In 1216 Morolo was devastated by Giovanni Ceccano, with the death of 424 inhabitants, those who had not been able to escape. In 1303 Thomas de Morolo was excommunicated by Pope Boniface VIII for having participated in the conspiracy of the slap of Anagni.
Since 1422 the Colonna controlled the fiefdom, which it held until the seventeenth century, when the papal authority took over.
Since the late nineteenth century, many inhabitants have migrated to different countries such that today there are more Morolani and their descendants outside of Italy.