Republicanism in Australia is a movement to change Australia's system of government from a constitutional monarchy to a republic; presumably, a form of parliamentary republic that would replace the monarch of Australia (currently King Charles III) with a non-royal Australian head of state. It is opposed to monarchism in Australia. Republicanism was first espoused in Australia before Federation in 1901. After a period of decline following Federation, the movement again became prominent at the end of the 20th century after successive legal and socio-cultural changes loosened Australia's ties with the United Kingdom.
In a referendum held in 1999, Australian voters rejected a proposal to establish a republic with a parliamentary appointed head of state. This was despite polls showing a majority of Australians supported a republic in principle for some years before the vote.