[2][3][4] In September 1939 she operated with Force H in the South Atlantic and Indian Ocean during the search for the enemy German raider Admiral Graf Spee.

Following the scuttling of Admiral Graf Spee in December 1939, Sussex returned to the UK, and served with the Home Fleet during the Norwegian Campaign.

She entered refit at Liverpool in March 1940 and in May after sea trials joined 1st Cruiser Squadron in Scapa Flow where she was deployed in search patrols and convoy duties.

[5] In August her crew detected a defect with her propulsion machinery so she was sent to Glasgow for repairs to her turbine blades, but while undergoing work, was struck by bombs on 18 September 1940.

HMS Sussex was paid off in 1949, handed over to the British Iron & Steel Corporation on 3 January 1950, and arrived at Dalmuir in Scotland on 23 February 1950 where she was broken up by W. H. Arnott, Young and Company, Limited.