The Roman Catholic Diocese of São Carlos (Latin: Dioecesis Sancti Caroli in Brasilia) is a diocese located in the city of São Carlos in the ecclesiastical province of Campinas in Brazil.

The diocese was established on 7 June 1908 as the Diocese of São Carlos do Pinhal from the Diocese of São Paulo.

On 25 November 1957, it was renamed as Diocese of São Carlos.

On 26 June 2024, the Diocese of Jaú was established from the ecclesiastical territory of São Carlos.

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