George Phillpotts was one of 14 children of Henry Phillpotts, vicar of St Margaret's, Durham, England, and later lord bishop of Exeter, and his wife, Deborah Maria Surtees; his date and place of birth are unknown, but he was baptised in Durham on 26 January 1814. It is not known whether he married. He entered the Royal Navy in 1827 and was senior lieutenant on the naval sloop Hazard, which arrived in New Zealand in July 1844.
In February 1845, in response to the growing tension in the Bay of Islands, the Hazard was dispatched to Kororareka (Russell), where her crew worked on the town's defences and attempted to counter attacks on the property of settlers in the area. Phillpotts took command of the settlement's militia. On 4 March 1845 he and a midshipman were captured near Kororareka by a group of Kawiti's warriors, but were later released unharmed.
Phillpotts took over command of the naval force when the Hazard's captain was badly wounded during Hone Heke and Kawiti's attack on Kororareka on 11 March. The loss of the flagstaff blockhouse left the British forces in a difficult position, and after a conference with the other officers, Phillpotts ordered the town's evacuation. Once the evacuation had been completed Phillpotts ordered the Hazard to bombard Kororareka, an act which may have precipitated the settlement's sacking. Those responsible for the defence of Kororareka have been much criticised, and certainly Phillpotts's inexperience and a want of sound judgement were evident during the battle. On 13 March the Hazard and the other ships carrying refugees from Kororareka sailed for Auckland after Phillpotts had decided that no useful purpose was served by remaining in the area.
The Hazard returned to the Bay of Islands in April, and during May Phillpotts led parties of seamen in operations against Hone Heke and Kawiti, including an expedition against a pa on the Waikare River. In June he was second in command of the Hazard's contingent which joined Colonel Henry Despard's expedition against Hone Heke and Kawiti at Ohaeawai. In the disastrous attack on the pa on 1 July 1845 Phillpotts led the party of seamen who formed part of the main body of the storming party. During the attack he shouted encouragement to his men, and ran along the face of the pa attempting to find a way in. Eventually he managed to get through the light outer stockade before being shot dead. After his death part of Phillpotts's scalp was removed by one of Ohaeawai's defenders, to be used by a tohunga to divine the future course of the war.
George Phillpotts, whose nickname was Toby, was a colourful character, well known for his eccentric behaviour and immoderate language. His rash and excitable nature led him to abuse Archdeacon Henry Williams and call him a traitor during the fighting at Kororareka, and to fight a duel with the owner of the Auckland Times. He was renowned for his courage, and was popular with his comrades and with the Maori, who regarded him as 'a generous, brave and good-natured man.' Going into the battle of Ohaeawai, he wore his monocle, 'a sailor's blue woollen shirt, tight cotton drawers, [and] boots', having discarded the soldier's trousers he had been wearing because he didn't 'want to die a soldier.'