The Roman Catholic Diocese of São Tomé and Príncipe (Latin: Sancti Thomae in Insula) is a diocese, immediately subject to the Holy See, with its seat in the city of São Tomé in São Tomé and Príncipe.
It covers the territory of the Republic of São Tomé and Príncipe.
As of 2015, 112,000 or 57.4% of the inhabitants of São Tomé and Príncipe were catholic.