Porto Velho is the capital city of northwest Brazil's Rondonia state. Located on the eastern shore of the Madeira River, one of the main tributaries of the Amazon River, it is 160 kilometers from the border with Bolivia. Covering 34 square kilometers, the city has a population of 426,558 people (as of the 2010 census). Porto Velho has a tropical climate with no dry seasons and the average monthly precipitation is about 60 millimeters.

Founded in 1914, Porto Velho is an important center for business and transport in northwest Brazil. It is also one of the fastest-growing cities in Brazil with a cluster of petrochemical, tin smelting, wood processing, building materials, food and aquaculture industries. The main modes of transport are rivers and railways. Porto Velho International Airport, which is only 7 km from the city, is served by 98 scheduled flights a week, most going to other large Brazilian cities. Two dams, Jirau and Santo Antonio, lie on the Madeira River, and cost $15 billion.

Many universities and research institutes are settled in Porto Velho, providing professionals for various industries. Portuguese is the official national, but English and Spanish are part of the official high school curriculum.

Porto Velho established sister city ties with Jinan, the capital city of East China's Shandong province, in October 2011.