The 4th Brigade is a brigade-level formation of the Australian Army. Originally formed in 1912 as a Militia formation, the brigade was re-raised for service during World War I, elements of the brigade served at Gallipoli and in the trenches on the Western Front before being disbanded in 1919. In 1921, the brigade was re-raised as a unit of Australia's part-time military forces, based in the state of Victoria. During World War II the brigade served in the New Guinea and New Britain campaigns. Following the war, the brigade formed part of the 3rd Division, however, it was later reallocated to the 2nd Division, where it serves as a Reserve combined-arms formation including units and personnel from all corps of the Army including armoured, infantry, artillery, engineers, signals and ordnance.

The 2nd Division of the Australian Army, also known as the 2nd (Australian) Division, commands all the Reserve brigades in Australia. These are the 4th in Victoria and Tasmania, the 5th in New South Wales, the 11th in Queensland, the 13th in Western Australia, and the 8th spread across the country. The division is also responsible for the security of Australia's northern borders through its Regional Force Surveillance Units.