The ship spent part of her early career in reserve before she was transferred to the 4th Cruiser Squadron (4th CS) of the North America and West Indies Station in mid-1914.

A few months later, Bristol played a minor role in the Battle of the Falkland Islands in December by sinking some of the colliers belonging to the German East Asia Squadron.

Bristol returned to her former task of patrolling off the east coast of South America, after a brief time escorting convoys off West Africa in early 1918, and continued to do so after the end of the war.

[4] In 1912 Bristol became the first warship to run on superheated steam from her twelve boilers, enabling even greater speeds as well as fuel economies.

[6] This armament was considered rather too light for ships of this size,[7] while the waist guns were subject to immersion in a high sea, making them difficult to work.

She arrived at Jamaica on the 31st and was ordered to depart for Mexico after recoaling to protect British interests during the ongoing Mexican Revolution.

Bristol spent most of June in Tampico, but sailed for Veracruz at the end of the month where Rear-Admiral Christopher Craddock, the squadron commander, inspected the ship and her crew on 1 July.

[14] The 4th Cruiser Squadron (formerly the North America and West Indies Station), with its main base the Royal Naval Dockyard at Bermuda, was tasked to protect Allied merchant shipping from commerce raiders in the Caribbean and along the East Coast of North America and Craddock dispersed his ships shortly before the war began on 4 August 1914 in a futile search for the two German warships known to be in the area.

[18] Upon arrival at Port Stanley on 7 December, Sturdee gave permission for Bristol to put out her fires to clean her boilers and repair both engines.

Vice-Admiral Maximilian von Spee, commander of the German squadron, had other plans and intended to destroy the radio station at Port Stanley on the morning of 8 December.

[20] Bristol spent the next several months hunting for the German cruiser along the Argentinian and Chilean coasts and in the innumerable bays and inlets of Tierra del Fuego.

On 26 November, Bristol sailed for Gibraltar en route to a refit at William Beardmore and Company's shipyard in Dalmuir that began on 17 December.

Bristol was the "ready ship" at Brindisi and was at a half-hour's notice for sea; she departed at 04:50, escorted by two Italian destroyers, in an attempt to intercept the three Austrian light cruisers that had conducted the attack.

Aquila opened fire at 08:15 at long range, but inflicted no damage before she was immobilised by a hit at 08:32 that detonated inside her central boiler room and severed her main steam pipe.

Both sides settled on parallel courses to the north-northwest and Bristol gradually began to fall behind and could eventually only use her bow gun at very long range before ceasing fire at 10:15.

She arrived on 17 January and departed on 2 April, bound for Sierra Leone, West Africa, to begin convoy escort duties[14] there despite being assigned to the East Coast of South America Station.

[24] On 1 May, Bristol departed Dakar, French West Africa, bound for the Brazilian coast, arriving at Rio de Janeiro on the 15th.

The ship patrolled the coasts of Brazil and Uruguay for the rest of the war and visited Port Stanley at the end of the year where she remained until 11 January 1919.