"Melbourne" stayed in Portsmouth until 7 March 1919, then sailed for Sydney via Suez, Singapore, and Darwin. The ship was paid off into reserve on 5 August 1919 until 14 April 1920, when she was recommissioned. In 1922, the ship rescued personnel from the sailing vessel "Helen B. Sterling", which had been disabled in the Tasman Sea by a gale. Also in 1922, the ship was assigned as Flagship of the Australian Squadron. She was returned to reserve on 29 September 1924; most of the four years in service had been spent in Australian waters, with cruises to New Zealand and the Pacific Islands. The cruiser was recommissioned on 8 October 1925, and left Sydney for England on 23 November. During 1926, the ship was assigned to the Mediterranean Fleet on exchange, with the British cruiser sent to operate with the RAN. "Melbourne" returned in August 1926, and resumed duties as Flagship.