The São Paulo Metro, commonly called the Metrô, is a rapid transit system that forms part of the urban railways that serves the city of São Paulo, alongside the São Paulo Metropolitan Trains Company (CPTM), both forming the largest metropolitan rail transport network of Latin America. The six lines in the metro system operate on 104.4 kilometres (64.9 mi) of route, serving 89 stations. The metro system carries about 4,300,000 passengers a day.

São Paulo is the most populous city in Brazil and the capital of the state of São Paulo. Listed by the GaWC as an alpha global city, São Paulo is the most populous city outside of Asia and the world's 20th-largest city proper by population. Additionally, São Paulo is the largest Portuguese-speaking city in the world. It exerts strong international influences in commerce, finance, arts, and entertainment. The city's name honors the Apostle, Saint Paul of Tarsus. The city's metropolitan area, the Greater São Paulo, ranks as the most populous in Brazil and the 12th-most-populous on Earth. The process of conurbation between the metropolitan areas around the Greater São Paulo created the São Paulo Macrometropolis, a megalopolis with more than 30 million inhabitants, one of the most populous urban agglomerations in the world.