The Australian flag uses three prominent symbols, the Union Flag (also known as the Union Jack), the Commonwealth Star and the Southern Cross. The Union Flag is commonly thought to reflect Australia's history as a collection of British colonies, although a more historic view sees its inclusion in the design as demonstrating loyalty to the British Empire. The five white stars of the fly of the flag represent the Southern Cross. The Southern Cross (or Crux) is the brightest constellation visible in the Southern Hemisphere and has been used to represent Australia and New Zealand since the early days of British settlement. Each of these stars has seven points except for the smallest star, which has only five. Ivor Evans, one of the flag's designers, intended the Southern Cross to refer also to the four moral virtues ascribed to the four main stars by Dante: justice, prudence, temperance and fortitude. The large seven-pointed star below the Union Flag is the Commonwealth or Federation Star, which represents the federation of the colonies of Australia on 1 January 1901. There is one point for each of the six original states and one to symbolise the Commonwealth's internal and external territories. The Commonwealth Star does not have any relation to Beta Centauri, despite that star's coincidental location in the sky and its brightness.

The blue colour has been described as representing Australia as an island continent, as a symbol of the journey humans had to make to reach Australia, as the blue sky, and as a remnant of the Eureka Flag, which also had a blue background.