Illicit drug use in Australia is the recreational use of prohibited drugs in Australia. Illicit drugs include illegal drugs, pharmaceutical drugs when used for non-medical purposes, and other substances used inappropriately. According to government and community organisations, the use and abuse, and the illegality, of illicit drugs is a social, health and legal issue that creates an annual illegal market estimated to be worth A$6.7 billion. Estimates made in 2022 place the figure at A$11.3 billion per year.

Cannabis is a plant used in Australia for recreational, medicinal and industrial purposes. In 2019, 36% of Australians over the age of fourteen years had used cannabis in their lifetime and 11.6% had used cannabis in the last 12 months.