George Samuel Graham was born at Auckland on 23 December 1874, the son of James Bannatyne Graham, a lawyer and insurance manager, and his wife, Elizabeth Mary Josephine Sheehan. His father was the son of George Graham, who had been a member of Governor William Hobson's military staff, MHR for Newton (1861–69), and negotiator for peace with Waikato Maori on behalf of Governor George Grey in the late 1860s. His mother was the sister of John Sheehan, native minister and minister of justice in Grey's ministry (1877–79).
The Graham family was Catholic, and George was educated at the Marist brothers' college and Queen's College, Auckland. After qualifying as an accountant he worked in the Bank of New Zealand from 1897. He then moved into law and accounting with Wynyard and Purchas in 1900 and the Commercial Union Assurance Company in 1912. He practised with his father from 1919 to 1929, and subsequently worked independently as an accountant and native agent. In this position, Graham gave priority to helping Maori families with legal, health and housing problems, usually without charge.
George Graham married Mary Magdalene Hapi on 4 April 1899 at St Patrick's Cathedral, Auckland. Born Takurangi Kahupeka Hapi, she had adopted Mary Magdalene as baptismal names. She was the daughter of Pataka Hapi of Waikato and Whatarangi Ngati of Ngati Whanaunga. There were seven children of this marriage. George and Mary Graham separated sometime after the birth of their last child in 1912. Graham later formed liaisons with Te Wharetoroa Tiniraupeka, also known as Margaret Graham, of Ngati Whakaue and Te Arawa, and with Mare Potatau of Ngati Mahuta; both relationships were childless. Mary Magdalene Graham died in 1935.
George Graham's family background and his relationships gave him a lifelong interest in Maori history, language, culture and artefacts. He drew on the knowledge of many Maori informants, mostly from Hauraki and Auckland, to compile a large number of manuscripts in these fields, many in Maori with a translation by him. He also collected the manuscripts of other authorities. Graham concentrated on the Tamaki area, collecting accounts of waka, waiata, whakapapa, taonga (treasures) and tikanga (customs). Three items from the collection were published: Fragments of ancient Maori history, collected by John McGregor and translated by Graham; 'The Maori history of the Auckland isthmus (Tamaki-makau-rau)'; and 'Before the Pakeha', on early invasions of Takapuna.
Perhaps the most significant manuscripts are translations Graham made of Tukumana Te Taniwha's 'Marutuahu', and Hoani Nahe's 'Hotunui'. Information also came from Paora Tuhaere of Ngati Whatua, Anaru Makiwhara of Ngai Tai, and others. Graham translated the 'Life and times of Te Rauparaha', written by his son, Tamihana Te Rauparaha; an account of the genealogy of the ancestors of Ngati Whatua, written by Paora Tuhaere; and the history of the tribes of Ngati Toa and Te Ati Awa.
Graham was a member of the Polynesian Society from 1902. He contributed a number of articles to its journal, of which perhaps 'Arawa notes' and 'The fall of Mokoia and Mauinaina and the death of Kaea' are the most significant. His Maori place names of Auckland, edited by D. R. Simmons, was published in 1980. In addition to his collecting and writing, Graham founded Te Akarana Maori Association, which fostered Maori knowledge in Auckland in the period from 1927 to 1949. He was a life member of the Auckland Institute and Museum, and the founder in 1922 of its Anthropology and Maori Race Section. He donated the Hori Montrose Graham Collection of artefacts. His collection of papers is divided between the Auckland City Library and the Auckland Institute and Museum Library.
George Graham retired in 1949, although he continued his collecting. He died at Rotorua on 11 April 1952, survived by three sons and two daughters. His understanding of and sympathy with Maori, and his scholarly and historical flair, had enabled him to make a valuable contribution to the preservation of written Maori knowledge.