The history of South Australia includes the history of the Australian state of South Australia since Federation in 1901, and the area's preceding Indigenous and British colonial societies. Aboriginal Australians of various nations or tribes have lived in South Australia for at least thirty thousand years, while British colonists arrived in the 19th century to establish a free colony. The South Australia Act, 1834 created the Province of South Australia, built according to the principles of systematic colonisation, with no convict settlers.

The Federation of Australia was the process by which the six separate British self-governing colonies of Queensland, New South Wales, Victoria, Tasmania, South Australia, and Western Australia agreed to unite and form the Commonwealth of Australia, establishing a system of federalism in Australia. The colonies of Fiji and New Zealand were originally part of this process, but they decided not to join the federation. Following federation, the six colonies that united to form the Commonwealth of Australia as states kept the systems of government that they had developed as separate colonies, but they also agreed to have a federal government that was responsible for matters concerning the whole nation. When the Constitution of Australia came into force, on 1 January 1901, the colonies collectively became states of the Commonwealth of Australia.