She served in the 2nd Cruiser Squadron during the First World War under Rear-Admiral Herbert Heath, taking part in the Battle of Jutland in 1916.

She was powered by a pair of four-cylinder triple-expansion steam engines, each driving one propeller shafts, which developed a total of 23,650 indicated horsepower (17,640 kW) and gave a maximum speed of 23.3 knots (43.2 km/h; 26.8 mph).

The ship carried enough coal and fuel oil to give her a range of 7,960 nautical miles (14,740 km; 9,160 mi) at a speed of 10 knots (19 km/h; 12 mph).

Twenty-six Vickers QF 3 pounders were fitted, ten on turret roofs and eight each on the forward and aft superstructures.

[4] Because of the extra topweight of the turrets in comparison to their half-sisters their stability was reduced which made them very good seaboats and steady gun platforms.

[8] She "joined the Nore Division of the Home Fleet on 6 March 1907 and shortly afterwards was brought into full commission for service with the 5th Cruiser Squadron.

[9] Cochrane, accompanied by her sister Achilles and three other armoured cruisers were sent to reinforce the defences of the Shetland Islands on 2 August 1914, days before the start of the First World War.

She took part in the Battle of Jutland on 31 May–1 June 1916, along with the armoured cruisers Minotaur, Shannon, and Hampshire under the command of Rear-Admiral Herbert Heath.

[12] Cochrane was transferred to the North America and West Indies Station, with its headquarters and Royal Naval Dockyard at the Imperial fortress colony of Bermuda, in November 1917, but rejoined the 2nd Cruiser Squadron early in 1918.