Mariana Pimentel is a municipality in the state of Rio Grande do Sul, Brazil.

It is located approximately 75 km from the state's capital, Porto Alegre.

Mariana Pimentel belongs to Porto Alegre Metropolitan Mesoregion and to Porto Alegre Microregion.

The outcrop Morro do Papaléo within Mariana Pimentel was the discovery site of two species of the extinct algae Brazilea, dating back to the Sakmarian of the Permian.

This geographical article relating to Rio Grande do Sul is a stub.