The Amalgamated Postal Workers' Union had its origins in the Australian Letter Carriers' Association which was registered federally in 1912. In 1924 it changed its name to the Commonwealth Public Service Fourth Division Employees' Union of Australia only to amalgamate a year later with the Postal Sorters' Union of Australia to form the Amalgamated Postal Linesmen Sorters' and Letter Carriers' Union of Australia. From 1926 it was known as the Amalgamated Postal Workers' Union and it survived until 1974 when it changed its name to the Australian Postal and Telecommunications Union.

The Australian Postal and Telecommunications Union was formerly the Amalgamated Postal Workers' Union, covering postmen, sorters and linesmen. In 1990 the union amalgamated with the Union of Postal Clerks and Telegraphists, then the Australian Postmasters' Association in 1991 and the Postal Supervisory Officers' Association in 1992 retaining its name until merging with the combined Australian Telecommunications Employees' Association and Australian Telephone and Phonogram Officers' Association to form the Communication Workers' Union of Australia later in 1992.