Emigrating from England for reasons of health, Eyre reached Australia in March 1833. As a sheep farmer he became a pioneer “overlander,” driving stock from Sydney to Adelaide. He explored the desert northwest of Adelaide and then (June 1840–July 1841) made an extremely hazardous journey around the Great Australian Bight. For several years he served as a magistrate and protector of Aborigines, whose language and customs he learned.

After leaving Australia in 1845, Eyre was lieutenant governor of New Zealand (1846–53) and of St. Vincent, in the West Indies (1854–60). His service as acting governor of the Leeward Islands (1860–61) and of Jamaica (1861–64) was rewarded with his permanent appointment as governor of Jamaica. On Oct. 11, 1865, a revolt by blacks began at Morant Bay, and, in the repression that followed, the total of executions passed 400. Eyre then caused the island's legislature to abolish itself and the Jamaican constitution (Jan. 17, 1866), whereupon Jamaica became a crown colony. After both commending Eyre for crushing the rebellion and censuring him for taking excessive reprisals, the British government recalled him in July 1866. Eyre's behaviour sparked an intense controversy among prominent British intellectuals; John Stuart Mill, Herbert Spencer, and Thomas Henry Huxley advocated his trial for murder, while his side was taken by Thomas Carlyle, John Ruskin, and Alfred, Lord Tennyson. A grand jury in London declined to indict him for murder (June 1868), and he was acquitted in a civil case brought against him by a Jamaican.