"Cardiff" arrived at Portsmouth on 11 January to begin a refit that lasted until 27 February. Her conning tower may have been removed at this time and the bridge enlarged. On 10 March, she sailed for Malta to join her squadron, which had been renumbered as the 3rd Light Cruiser Squadron (3rd LCS) and assigned to the Mediterranean Fleet while the ship was refitting, where she arrived on six days later. The squadron was assigned peacekeeping duties in the Adriatic for most of 1919 and "Cardiff" spent the time visiting various Adriatic ports or in Malta. She became the flagship of Rear-Admiral George Hope on 1 September.