Valparaíso (; Spanish: [balpaɾaˈiso]) is a major city, commune, seaport, naval base, and educational centre in the Valparaíso Region, Chile.

"Greater Valparaíso" is the second largest metropolitan area in the country. Despite only being the second largest city in the metropolitan area of Greater Valparaíso, with the first being Viña del Mar, Valparaíso serves as the namesake for the region due to its historical and cultural significance. Valparaíso is located about 120 km (75 mi) northwest of Santiago by road and is one of the Pacific Ocean's most important seaports. Valparaíso is the capital of Chile's second most populated administrative region and has been the headquarters for the Chilean Navy since 1817 and the seat of the Chilean National Congress since 1990.

Valparaíso played an important geopolitical role in the second half of the 19th century when it served as a major stopover for ships traveling between the Atlantic and Pacific oceans by crossing the Straits of Magellan. Valparaíso experienced rapid growth during its golden age, as a magnet for European immigrants, when the city was known by international sailors as "Little San Francisco" and "The Jewel of the Pacific". Notable inheritances from its golden age include Latin America's oldest stock exchange, the continent's first volunteer fire department, Chile's first public library, and the oldest Spanish language newspaper in continuous publication in the world, El Mercurio de Valparaíso. In 2003, the historic quarter of Valparaíso was declared a UNESCO World Heritage Site.

The twentieth century was unfavorable to Valparaíso, as many wealthy families abandoned the city. The opening of the Panama Canal in 1914 and the associated reduction in ship traffic dealt a serious blow to Valparaíso's port-based economy. In the 21st century the port of San Antonio has surpassed Valparaíso in trade volume (TEU) handled, leading to the questioning of its traditional moniker Puerto Principal ("Main Port" of Chile).

Over the first 15 years of the twenty-first century, the city reached a recovery, attracting artists and cultural entrepreneurs who have set up in the city's hillside historic districts. Today, many thousands of tourists visit Valparaíso from around the world to enjoy the city's labyrinth of cobbled alleys and colorful buildings. The port of Valparaíso continues to be a major distribution center for container traffic, copper, and fruit exports. Valparaíso also receives growing attention from cruise ships that visit during the South American summer. Most significantly, Valparaíso has transformed itself into a major educational center with four large traditional universities and several large vocational colleges. The city is known for its bohemian culture, with festivals every year, and street artists and musicians.