The C-class cruisers were intended to escort the fleet and defend it against enemy destroyers attempting to close within torpedo range.

[4] Cambrian was powered by four direct-drive Parsons steam turbines, each driving one propeller shaft, which produced a total of 40,000 indicated horsepower (30,000 kW).

She was commissioned into service that same month and was assigned to the 4th Light Cruiser Squadron of the Grand Fleet in which she served through the end of World War I and until 1919.

The squadron was briefly detached from the Grand Fleet in March 1917 to fruitlessly patrol off the Norwegian coast when news of a blockade runner was received by the Admiralty.

[9] At the beginning of 1919, Cambrian was refitted in Rosyth before she sailed for Devonport where she was visited by the Edward, Prince of Wales on 13 June.

Cambrian's crew spent several days in August trying to tow off the schooner Bella Scott after she had run aground near Kingston, Jamaica and received a brief refit in Bermuda in March–April 1920.

[10] She was part of the 2nd Light Cruiser Squadron of the Atlantic Fleet from August 1922 until June 1924, and was detached to support British interests during the Chanak Crisis of 1922–23.

[4] She escorted the seaplane carrier Ark Royal from the UK to Turkey from 27 September to 8 October and was later guard ship at Smyrna in December.