Arienzo is a town and comune in the Province of Caserta, Campania, southern Italy.

On the hill above the town are the ruins of the medieval castle dismantled by Roger II of Sicily in 1135 during his struggle against rebellious barons.

The Capuchin monastery situated on a nearby hill and immersed in its own citrus tree orchard was built in 1561, though the church was rebuilt in the 18th century.

Saint Leopoldo Mandic lived here for a year towards the end of World War I. Giacomo Furia, the theatre and film actor, was born in Arienzo.

St. Alphonse Liguori, bishop of St. Agatha of the Goths, made this his episcopal residence when his health began to decline.