The King's Birthday is an annual public holiday celebrated in the state of Queensland (QLD) in Australia. This holiday recognises the birthday of the reigning monarch. Its date varies but it usually falls on the first Monday in October. Despite its name, the King's Birthday celebration is not necessarily on the actual birth date of the present king or queen, but rather on a day assigned by the government.

This holiday was originally started to celebrate the birthday of King George V, but it has since been adapted to commemorate the lives of any installed Monarchs. During King's Birthday, communities across Queensland often organise local festivities. These may include parties, concerts, and parades. Corporate offices and schools in Queensland are closed on the King's Birthday, and many people enjoy a long weekend with their friends and families.

The King's Birthday illustrates Australia's historical ties with the British monarchy and its tradition of honouring the reigning monarch. The holiday highlights the cultural significance of the monarchy within Australia, particularly in the state of Queensland. Moreover, the extended weekend gives Australians the opportunity to celebrate their rich heritage and diverse culture, strengthening the community spirit and patriotic feeling among Queenslanders.