The province largely follows the territory of the low and middle Latin Valley, a larger region that extends from south of Rome to Cassino.

In the 7th century BC, the area of what is now the province entered the orbit of Rome, which made it the so-called Latium adiectum ("Adjoined Lazio").

After the fall of the Western Roman Empire, the northern part of the province (officially referred to as Campagna since the 12th century[5]) belonged to the Papal States, while the region south of the Liri orbited around the powers of Benevento and then Naples.

After the unification of Italy, in 1927 the Fascist government made Frosinone the capital of a province which unified different areas that belonged to the Papal and Neapolitan states.

This action generated criticism, as these states were considered too different in history, language and culture, especially by the Bourbon-nostalgic party that maintained a strong position in southern Italy for many decades.