The Australia Act 1986 is the short title of each of a pair of separate but related pieces of legislation: one an act of the Parliament of Australia, the other an act of the Parliament of the United Kingdom. In Australia they are referred to, respectively, as the Australia Act 1986 (Cth) and the Australia Act 1986 (UK). These nearly identical Acts were passed by the two parliaments, because of uncertainty as to whether the Commonwealth Parliament alone had the ultimate authority to do so. They were enacted using legislative powers conferred by enabling Acts passed by the parliaments of every Australian state. The Acts came into effect simultaneously, on 3 March 1986.

The Parliament of Australia is the legislative body of the federal level of government of Australia. It consists of three elements: the monarch, the Senate and the House of Representatives. It combines elements from the UK Parliament and the US Congress.