The Roman Catholic Diocese of Zárate-Campana (Latin: Dioecesis Zaratensis-Campanensis) is a Latin rite suffragan diocese in the ecclesiastical province of the Archdiocese of Mercedes-Luján, in central Argentina on the Atlantic coast, having had a change of metropolitan from La Plata in 2019.

Its cathedral episcopal see is Catedral Santa Florentina, dedicated to Saint Florentina, in Campana, and it also has a co-cathedral: Cocatedral Natividad del Señor, dedicated to the Nativity of Our Lord, in Belén de Escobar, also in Buenos Aires Province.

It was created by Pope Paul VI on 21 April 1976, by the Papal Bulla "Qui consilio divino" as Diocese of Zárate–Campana / Zaraten(sis)–Campanen(sis) (Latin adjective), on territories split off from the Diocese of San Isidro and from the Diocese of San Nicolás de los Arroyos.

Alfredo Mario Espósito Castro, chosen by Paul VI on 21 April 1976, received his episcopal consecration and took possession of the see on 4 July 1976.

As of 2014, it pastorally served 660,000 Catholics (90.7% of 728,000 total) on 5,924 km² in 33 parishes and 89 missions with 88 priests (53 diocesan, 35 religious), 13 deacons, 178 lay religious (88 brothers, 90 sisters) and 27 seminarians.