O Porriño is a municipality in Galicia, Spain in the province of Pontevedra.
An industrial town, in the Vigo metropolitan area, it is an important economic dependency. One of its main industries is granite production; the variety of granite produced in O Porriño is known as Rosa Porriño, and is exported from the Port of Vigo mainly to Italy, Japan and China.
From O Porriño came the architect Antonio Palacios, known for the use of granite in his work, such as the Telecommunications Palace in Madrid, the García Barbón Theater in Vigo, or Porrino Town Hall amongst others.
It is the home town of the Sporting Lisboa woman basketball team player Andrea Pérez Alonso.
On 9 September 2016, a Portuguese train travelling from Vigo to Porto derailed near O Porriño railway station, killing the driver and at least three other people on board.