São Paulo (, Portuguese: [sɐ̃w ˈpawlu] (listen); Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC as an alpha global city, São Paulo is the most populous city proper in the Americas, the Western Hemisphere, and the Southern Hemisphere, as well as the world's 4th 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 (Campinas, Santos, Jundiaí, Sorocaba and São José dos Campos) created the São Paulo Macrometropolis, a megalopolis with more than 30 million inhabitants, one of the most populous urban agglomerations in the world.

Having the largest economy by GDP in Latin America, the city is home to the São Paulo Stock Exchange. Paulista Avenue is the economic core of São Paulo. The city has the 23rd largest GDP in the world, representing alone 10.7% of all Brazilian GDP and 36% of the production of goods and services in the state of São Paulo, being home to 63% of established multinationals in Brazil, and was responsible for 28% of the national scientific production in 2005, as measured by the number of science papers published in journals.

The metropolis is also home to several of the tallest skyscrapers in Brazil, including the Mirante do Vale, Edifício Itália, Banespa, North Tower and many others. The city has cultural, economic and political influence nationally and internationally. It is home to monuments, parks and museums such as the Latin American Memorial, the Ibirapuera Park, Museum of Ipiranga, São Paulo Museum of Art, and the Museum of the Portuguese Language. The city holds events like the São Paulo Jazz Festival, São Paulo Art Biennial, the Brazilian Grand Prix, São Paulo Fashion Week, the ATP Brasil Open, the Brasil Game Show and the Comic Con Experience. São Paulo's LGBT Pride parade ranks second only to the New York City Pride March as the largest LGBTQ pride parade in the world.

São Paulo is a cosmopolitan, melting pot city, home to the largest Arab, Italian, Japanese, and Portuguese diasporas, with examples including ethnic neighborhoods of Bixiga, Bom Retiro, and Liberdade. In 2016, inhabitants of the city were native to over 200 countries. People from the city are known as paulistanos, while paulistas designates anyone from the state, including the paulistanos. The city's Latin motto, which it has shared with the battleship and the aircraft carrier named after it, is Non ducor, duco, which translates as "I am not led, I lead." The city, which is also colloquially known as Sampa, Selva de Pedra (Jungle of Stone) or Terra da Garoa (Land of Drizzle), is known for its unreliable weather, the size of its helicopter fleet, its architecture, gastronomy, severe traffic congestion and skyscrapers. São Paulo was one of the host cities of the 1950 and the 2014 FIFA World Cup. Additionally, the city hosted the IV Pan American Games, Miss Universe 2011, and the São Paulo Indy 300.