Line 3 (Red) (Portuguese: Linha 3–Vermelha) is one of the six lines that make up the São Paulo Metro and one of the thirteen lines that make up the Metropolitan Rail Transportation Network. It runs between Palmeiras-Barra Funda and Corinthians-Itaquera. It was formerly called the East-West Line. Line 3 is the busiest in the system.

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.