The deputy premier of Western Australia is a role in the Government of Western Australia assigned to a responsible Minister in the Australian state of Western Australia. It has second ranking behind the premier of Western Australia in Cabinet, and its holder serves as acting premier during absence or incapacity of the premier. The role was only formally established on 7 December 1955, but had existed in practice since the earliest days of responsible government.

The Government of Western Australia is the Australian state democratic administrative authority of Western Australia. It is also commonly referred to as the WA Government or the Western Australian Government. The Government of Western Australia, a parliamentary constitutional monarchy, was formed in 1890 as prescribed in its Constitution, as amended from time to time. Since the Federation of Australia in 1901, Western Australia has been a state of the Commonwealth of Australia, and the Constitution of Australia regulates its relationship with the Commonwealth. Under the Australian Constitution, Western Australia ceded legislative and judicial supremacy to the Commonwealth, but retained powers in all matters not in conflict with the Commonwealth.