Line 4 (São Paulo Metro)

Line 4 (Yellow) (Portuguese: Linha 4–Amarela) is one of the six lines that make up the São Paulo Metro and one of the thirteen lines that make up the São Paulo Metropolitan Rail Transportation Network. Originally called Southeast-Southwest Line, the line goes from Vila Sônia to Luz and currently has 11 stations along its 12.8 km (8.0 mi) and transports around 800,000 users/day. It is the most modern subway line in Latin America and the first line in the region to utilize driverless trains and platform screen doors in all stations.

The construction of the line was divided into two phases: The phase one was completed in 2011 and the phase two was partially inaugurated between 2014 and 2018 and was fully completed by 2021.

Now completed, Line 4 - Yellow goes from Vila Sônia to Luz station, in a 12.8 km (8.0 mi) long stretch. An expansion was announced in April 2025 that will add 3.3 km (2.1 mi) and two new stations, with an expected opening by 2028. It is operated by ViaQuatro, a private company which won the public-private partnership to operate Line 4 for 30 years, which can be renewable for another 30 years. Companhia do Metropolitano de São Paulo, the company operates some other lines in the São Paulo Metro, monitors the operation of the line.