Naturalist, explorer, governor and politician, Grey studied the Indigenous languages and cultures of Australia, New Zealand and South Africa, leaving 'a deep impression on three great colonial areas' (ctd. Australian Dictionary of Biography).

After completing his military training Grey became an ensign in the 83rd Regiment in Ireland. 'Through sympathy for Irish peasants he [eventually] became interested in systematic colonization as a cure for their distress, and his attention was drawn to Australian exploration by Charles Sturt's discoveries ... In 1836 he left Ireland and wrote to the Colonial Office offering to lead an expedition to seek a site for settlement in north-western Australia' (ctd. Australian Dictionary of Biography).

Grey's plan was supported by the Royal Geographical Society and, after its approval by the Colonial Office, he sailed for Western Australia in the Beagle in July 1837. From Cape Town, South Africa, he charted the schooner Lynher and reached Hanover Bay, near Collier Bay, in the north of Western Australia in December 1837. He explored inland from 29 January 1838 to April 1838, surviving a spearing . His party was rescued by the Beagle and the Lynher. After recuperating in Mauritius Grey returned to Western Australia arriving in Perth in September 1838. He undertook further exploration in February 1839 from Shark Bay aiming to travel to the North-West Cape. After, again, a journey of much hardship and danger he arrived back in Perth on 21 April 1839.

In June 1839 Grey was promoted captain and in August appointed resident magistrate at King George Sound, Western Australia. He published Vocabulary of the Aboriginal Language of Western Australia in serialised form in the Perth Gazette and Western Australian Journal, August - October 1839 and in pamphlet form as Vocabulary of the Dialects Spoken by the Aboriginal Races of S. W. Australia in November 1839. A second edition was published in London in 1840. The ADB notes that 'his "report on the best means of promoting the civilization of the Aboriginal Inhabitants of Australia" was circulated by the Colonial Office to the governors of other colonies.' Throughout his life he was an advocate for 'compulsory assimilation'.

Between short periods of leave in England, Grey was appointed governor of South Australia, 1841 - 1845, governor of New Zealand, 1845 - 1853, governor of Cape Colony and high commissioner of South Africa, 1854 - 1861 and governor of New Zealand for the second time 1861 - 1868. He was dismissed from his New Zealand post in 1868 and returned to England only to travel back to New Zealand in 1870 to retire. He entered politics in New Zealand in 1874. As late as 1891 he visited Australia attending the Australian Federal Convention 'and with senile garrulity championed the principle of "one man one vote", and then toured the main eastern towns preaching pure democracy and social equality...'

Grey returned to London for the final time in 1894 where he died in 1898.