Established in 1851, the original Amalgamated Engineering Union was a branch of the British union. It was registered with the Commonwealth Conciliation and Arbitration Court in 1905 and became known as the Amalgamated Society of Engineers. In 1920 it amalgamated with ten other engineering and allied trade unions and changed its name to the Amalgamated Engineering Union, Australian Section in 1921. In 1968 the union became autonomous from its parent body in Britain, shortening its name to the Amalgamated Engineering Union to reflect this. In mid-June 1972 the AEU began a series of amalgamations with the Sheet Metal Workers, Blacksmiths & Boilermakers and Federated Jewellers to form the Amalgamated Metal Workers' Union by 1973.

The Boilermakers' and Blacksmiths' Society of Australia was formed in 1965 when members of the deregistered Blacksmiths' Society of Australia joined the Boilermakers' Society of Australia. In 1973 it joined the Amalgamated Engineering Union and the Sheet Metal Workers to form the Amalgamated Metal Workers' Union.

The union was originally registered as the Amalgamated Tinsmiths' Sheet Metal Workers' Cannister Makers' Gas Meter Makers' & Assistants' Union in 1911 and comprised of unions that had operated since 1881. From 1913 its name changed to the Sheet Metal Working Industrial Union of Australia. In 1945 the union changed its name to the Sheet Metal Working Agricultural Implement & Stove Making Industrial Union of Australia to reflect growing membership from members of the Federated Agricultural Implement & Stovemakers' Porcelain Enamellers' & Ironworkers' Association of Australia. It was deregistered in 1972 and joined the Amalgamated Engineering Union to form the Amalgamated Metal Workers' Union in 1973.