Portuguese colonization of the Americas constituted territories in the Americas belonging to the Kingdom of Portugal. Portugal was the leading country in the European exploration of the world in the 15th century. The Treaty of Tordesillas in 1494 divided the Earth outside Europe into Castilian and Portuguese global territorial hemispheres for exclusive conquest and colonization. Portugal colonized parts of South America, but also made some unsuccessful attempts to colonize North America.

The Treaty of Tordesillas, signed in Tordesillas, Spain, on 7 June 1494, and ratified in Setúbal, Portugal, divided the newly discovered lands outside Europe between Portugal and the Crown of Castile, along a meridian 370 leagues west of the Cape Verde islands, off the west coast of Africa. That line of demarcation was about halfway between Cape Verde and the islands visited by Christopher Columbus on his first voyage, named in the treaty as Cipangu and Antillia.