Alumínio is a municipality in the state of São Paulo, Brazil. It forms part of the Metropolitan Region of Sorocaba and lies east of the city of Sorocaba, functioning in part as a suburban area of that urban centre.
The municipality covers an area of 83.66 km² and sits at an elevation of 790 metres. Its population was recorded as 18,767.
The main employer in Alumínio is Companhia Brasileira de Alumínio, the company with which the town's name is associated.