The Diocese of Acerra (Latin: Dioecesis Acerrarum) is a Latin diocese of the Catholic Church in Campania, southern Italy, eight miles east of Naples, in the area once called Terra Laboris (Liburia).

[1] The cathedral was administered and served by a Chapter, composed of three dignities (the Archpriest, the Cantor, and the Primicerius) and fifteen Canons.

Pope Pius VII, in the bull "De Utiliori" of 27 June 1818, chose to unite the two dioceses under the leadership of one bishop, aeque principaliter.

[6] In the same concordat, the King was confirmed in the right to nominate candidates for vacant bishoprics, subject to the approval of the pope.

In the bull, Pope Pius also transferred four communes from S. Agata to Acerra: Arienzo, San Felice, S. Maria a Vico, and Cervino and the farm of Forchia.