In 1924 the Railway and Tramway Officers' Association (registered in New South Wales in 1913) amalgamated with the first federally registered organisation of salaried officers, the Victorian Railways Administrative Officers' and Clerks' Association (formed in 1921) to become the Australasian Transport Officers' Federation. It changed its name in 1978 to the Australian Transport Officers' Federation. The Airlines Division held its inaugural meeting on 22 November 1980. By 1991 the union had merged with the Technical Service Guild of Australia and the Municipal Officers' Association of Australia to form the Australian Municipal Transport Energy Water Ports Community and Information Services Union. Further amalgamations in 1992 and 1993 with the Australian Social Welfare Union, the Australian Shipping and Travel Officers' Association, the Federated Clerks' Union and the Federated Municipal and Shire Council Employees' Union formed the Australian Municipal Administrative Clerical and Services Union, known as the Australian Services Union.

Formed from the Australian Association of Social Workers, which had been in existence since 1955, the Australian Social Welfare Union came into being in 1976. In 1992, it amalgamated into the Australian Municipal Transport Energy Water Ports Community and Information Services Union, known as the Australian Services Union. Members of the Australian Social Welfare Union now form the Social and Community Services Sector Industry Division at a Branch and National level. The addition of the SACS area into the ASU provided a vital link into the private sector, bringing together workers within local government with their colleagues employed by non-government agencies.

Formed originally in 1942 as the Australian Shipping Officers' Association, the union changed names in 1988 to the Australian Shipping and Travel Officers' Association. In 1993 it amalgamated with the Australian Municipal Transport Energy Water Ports Community and Information Service Union, which after further amalgamations later that year became the Australian Municipal Administrative Clerical and Services Union, known as the Australian Services Union.

The union known as the Australian Services Union began in 1991 as an amalgamation of the Technical Service Guild of Australia, the Municipal Officers' Association of Australia and the Australian Transport Officers' Federation and took the name the Australian Municipal Transport Energy Water Ports Community and Information Services Union. It retained this name after amalgamation with the Australian Social Welfare Union and the Western Australian Railway Officers' Association in 1992 and with the Australian Shipping and Travel Officers' Association in 1993, but changed its name to the Australian Municipal Administrative Clerical and Services Union later in 1993 after amalgamation with the Federated Clerks' Union of Australia and the Federated Municipal and Shire Council Employees' Union of Australia. In 1994, the Totalisator Employees' Association of Victoria was incorporated in the union.

The Railway and Tramway Officers' Association was registered in New South Wales in 1913 and amalgamated with the Victorian Railways Administrative Officers' and Clerks' Association to form the Australian Transport Officers' Federation in 1924.