On the outbreak of World War I in 1914 she was in the West Indies and was the first British ship to see action, engaging the German raider Karlsruhe which used her superior speed to escape. By early December 1914 she formed part of the squadron sent to avenge the defeat at Coronel, and was refueling with coal in the harbour of Port Stanley on the morning of 8 December. Because of this, she was two hours late in joining the chase which was the Battle of the Falkland Islands and consequently did not engage the main enemy force, instead attacking two collier ships instead.
She later joined the Adriatic Squadron under an Italian admiral and fought Austrian raiders which escaped.
HMS Bristol was scrapped in Cornwall in 1921.