The Diocese of São João del Rei (Latin: Dioecesis Sancti Ioannis a Rege) is a Latin Church ecclesiastical jurisdiction or diocese of the Catholic Church in Brazil.

It is a suffragan in the ecclesiastical province of the metropolitan Archdiocese of Juiz de Fora.

[1] Its cathedral is the Cathedral Basilica of Our Lady of the Pillar, São João del Rei, a minor basilica, dedicated to Our Lady of the Pillar, in the city of São João del-Rei.

As of 2015[update], its pastoral services reached 506,000 Catholics (85.1% of the total population, 594 800), on 9 503 km², and 40 parishes.

This article on a Roman Catholic diocese in Brazil is a stub.