Casalvieri (Campanian: Casaluere) is a comune (municipality) in the Province of Frosinone in the Italian region Lazio, located about 110 kilometres (68 mi) southeast of Rome and about 30 kilometres (19 mi) east of Frosinone.

Casalvieri borders the following municipalities: Alvito, Arpino, Atina, Casalattico, Fontechiari, Vicalvi.