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

The ships carried enough fuel oil to give them a range of 3,680 nautical miles (6,820 km; 4,230 mi) at 18 knots (33 km/h; 21 mph).

Sometime between 1919 and 1924 the ship received a pair of two-pounder (1.6-inch (40 mm)) Mk II "pom-pom" AA guns on single mounts.

All of these changes adversely affected the ship's stability and the additional 21-inch torpedo tubes and the aft control position were removed by the end of 1921.

Commissioned into service in that same month, Carysfort was assigned to the 4th Light Cruiser Squadron (4th LCS) of the Grand Fleet in August 1915.

[11] Early that month, the squadron was dispatched to patrol off the Norwegian coast in search of the German commerce raider Meteor which was trying to return to Germany.

[12] In April 1916, she relieved her damaged sister HMS Conquest in the 5th Light Cruiser Squadron in the Harwich Force, which operated in the North Sea to guard the eastern approaches to the Strait of Dover and English Channel, and so did not participate in the Battle of Jutland a month later.

Tyrwhitt then ordered Canterbury and her escort to intercept the fleeing Germans; they spotted six torpedo boats about a half-hour later and opened fire at 02:02.

Visibility was poor because of another smoke screen laid by the Germans and the British ships were forced to disengage without inflicting any damage at 02:25 as they were approaching a minefield.

These reports, however, did persuade Admiral Reinhard Scheer, commander of the High Seas Fleet, to abandon his attack and turn for home.

Losses to submarines and mines during the operation persuaded the British that it was too risky to deploy major forces in the southern part of the North Sea.

The Admiralty ordered Tyrwhitt to detach Carysfort and four destroyers to reinforce Vice-Admiral Reginald Bacon's Dover Patrol as they feared that the transfer was in preparation for a concerted attack on the shipping protected by the latter.

[19] In December, Carysfort collided with the merchant ship SS Glentaise in the North Sea off Orford Ness, Suffolk, England.