Shortly after the war began, the ship searched unsuccessfully for the German East Asia Squadron and was transferred to the Grand Fleet at the end of 1914.

During the rest of the war Minotaur served as the flagship of the 7th and 2nd Cruiser Squadrons and spent most of her time assigned to the Northern Patrol.

She was powered by a pair of four-cylinder triple-expansion steam engines, each driving one shaft, which developed a total of 27,000 indicated horsepower (20,130 kW) and gave a maximum speed of 23 knots (43 km/h; 26 mph).

She escorted the royal yacht Victoria and Albert from Kiel, Germany to Reval when King Edward VII and his wife visited in Russia in June.

The next month Minotaur escorted the battlecruiser Indomitable as it carried the Prince of Wales to Canada to commemorate the tercentenary of Quebec City.

She was present for two fleet reviews in June and July before she was ordered to the China Station in January 1910 to relieve King Alfred as flagship.

[6] The ship was detached from the convoy and ordered to proceed to the Cape of Good Hope and reinforce the squadron there on 6 November after the Admiralty learned of the defeat at the Battle of Coronel.

[7] Upon her arrival Minotaur became flagship of the Cape of Good Hope Station under the command of Vice Admiral Herbert King-Hall and escorted a South African troop convoy to Luderitz Bay in German South-West Africa.

[9] Upon her arrival, Minotaur became flagship of the 7th Cruiser Squadron, under the command of Rear Admiral Arthur Waymouth,[10] based at Cromarty Firth.

[6] The ship was transferred to the 2nd Cruiser Squadron on 30 May 1916 and participated in the Battle of Jutland on the following day as flagship of Rear Admiral Herbert Heath.