San Miguel das Negradas (officially San Miguel de Negradas) is a civil parish in the municipality of O Vicedo, in the A Mariña Occidental comarca of the Province of Lugo, Galicia, northwestern Spain. It lies on the border with Mañón in the Province of A Coruña, at the mouth of the Sor River where it forms the Ría do Barqueiro. The parish includes the island of San Martiño.
The coastal zone falls within the Costa da Mariña Occidental Natura 2000 protected area. San Miguel das Negradas has lost population steadily over recent decades — the 2025 Padrón recorded 136 residents.
Following the Spanish Constitution of 1812, the territory was organised into three separate municipalities: Negradas, Val, and Cabanas. This lasted only a few years; by 1840 the parishes had been folded into the municipality of Riobarba, renamed O Vicedo in 1952. The island of San Martiño lies within the parish at the mouth of the Sor. The coastal area is designated as the Costa da Mariña Occidental Natura 2000 Lugar de Interese Comunitario (LIC). The 2025 Padrón recorded 136 residents.