The Health Services Union of Australia was formed in January 1991 by the amalgamation of the Health and Research Employees Association and the Hospital Employees Federation of Australia. On 1 October 2003 the union changed its name to the Health Services Union.

The Health and Research Association of Australia (HAREA) was registered in 1969 and united unions which had previously functioned only at state level. In 1969 the Australian National University General Staff Association transferred its industrial functions to HAREA which established a Federal Sub-Branch at the Australian National University. HAREA already had coverage of general staff at the University of Sydney, Macquarie University and the University of New England. Two other Federal Sub-Branches of HAREA were formed at the Canberra College of Advanced Education and the University of Tasmania. An autonomous Branch of HAREA was formed in the Australian Capital Territory on 1 October 1988. The ANU and CCAE Sub-Branches became sub-Branches of the ACT Branch. In January 1991 HAREA amalgamated with the Hospital Employees' Federation of Australia to form the Health Services Union of Australia. Following formation of the Health Services Union of Australia, the ACT Branch of HAREA became the Health Services Union of Australia, ACT No.2 Higher Education Branch. The Sub-Branches at the ANU and the University of Canberra continued to operate under the auspices of the ACT No.2 Branch.

The Hospital Employees' Federation of Australia traces its history back to 1911 when it operated under the name of the Hospital and Asylum Attendants & Employees' Union. In 1914 the name was changed to the Hospital Dispensary and Asylum Employees' Union of Australia and again in 1930 to the Hospital, Dispensary and Asylum Employees' and Allied Government Officers' Federation of Australia. In 1946 the name was changed to the Hospital Employees' Federation of Australasia which became the Hospital Employees' Federation of Australia in 1959. In January 1991, the Hospital Employees' Federation of Australia amalgamated with the Health and Research Employees' Association to form the Health Services Union of Australia. Following formation of the HSUA, the Australian Capital Territory Branch of the Hospital Employees' Federation of Australia became the ACT No.1 Branch of the HSUA.