[2] Upon completion, Viceroy was assigned to the Grand Fleet, based at Scapa Flow in the Orkney Islands, in which she served for the rest of World War I.

[2] In 1921, Viceroy joined the light cruisers Caledon, Castor, Cordelia, and Curacoa and the destroyers Vanquisher, Vectis, Venetia, Violent, Viscount, Winchelsea, and Wolfhound in a Baltic cruise, departing the United Kingdom on 31 August 1921.

The ships crossed the North Sea and transited the Kaiser Wilhelm Canal to enter the Baltic, where they called at Danzig in the Free City of Danzig; Memel in the Klaipėda Region; Liepāja, Latvia; Riga, Latvia; Tallinn, Estonia; Helsinki, Finland; Stockholm, Sweden; Copenhagen, Denmark; Gothenburg, Sweden; and Kristiania, Norway, before crossing the North Sea and ending the voyage at Port Edgar, Scotland, on 15 October 1921.

[2] Viceroy's conversion had not yet begun when the United Kingdom entered World War II on 3 September 1939, and she remained out of commission in reserve.

[2] Viceroy continued on her North Sea duties until reassigned in May 1943 to the support of the upcoming Allied invasion of Sicily, Operation Husky, scheduled for July 1943.

[2] After the surrender of Japan on 15 August 1945, Viceroy was decommissioned and placed in reserve,[2] being no longer carried on the Royal Navy's active list by October 1945.