The Royal Australian Navy officially came into being carrying that name on July 10th 1911, when the King, George V approved the Royal moniker being added to the Australian Navy. Australian Warships were to carry the prefix HMAS, meaning His Majesties Australian Service, and were to carry the White Ensign at the stern and the Australian Flag at the jackstaff. HMAS Australia was to be the 19200 tonne flagship of the RAN fleet and sailed from Portsmouth on the 21st of July 1913 and reached Sydney on the 4th of October of the same year sailing into the Harbour with the HMAS ships Melbourne, Encounter, Sydney, Parramatta and Yarra.

At the beginning of World War I, HMAS Australia sailed for New Guinea in search of the German Pacific Fleet but the German ships were sailing for South America and the Australia Squadron failed to detect them. HMAS Australia was then sent to Scapa Flow to operate with the Royal Navy and became the flagship of the 2nd Battle Cruiser squadron with HMS New Zealand and HMS Indefatigable. HMAS Australia during this period was to collide with HMS New Zealand and the damage kept HMAS Australia in the dockyards until 9th of June 1916, hence missing the Battle of Jutland.

HMAS Australia was used at differant times through 1918 in experiments for aircraft flying off platforms constructed on the turrets of the ship. Previously aircraft on Battlecruisers and Battleships had been floatplanes, but the aircraft being experimented with were standard fixed undercarriage aircraft. HMAS Australia during these trials carried a Sopwith Strutter on the fore amidships turret and a Sopwith Camel on the aft amidships turret.

On the 23rd of April HMAS Australia left Portsmouth for Australia and reached Sydney on the 15th of June 1919. She was paid off on the 23rd of December 1919. HMAS Australia unfortunately was to be a casualty of the Washington treaty of 1922 which limited naval strengths, and she was scrapped before being towed out to sea by tug and sunk 24 miles from South Head on 12th of April 1924.