Edward Osborne Hewett was born on September 25, 1835, in Southsea, Hampshire, England.

He was a British army officer, military engineer, and college commandant. He was educated at Cheltenham College and the Royal Military Academy, Woolwich and served in the Crimean War in 1854-1855. After taking courses in military surveying and engineering, Hewett was employed at Dover on the construction of forts. In 1857, he was posted to the West Indies as a commanding engineer. Promoted captain in 1860, he became an assistant instructor at the Royal Military Academy. In 1861, he arrived in British North America, where he was appointed commanding engineer west of Hamilton, Ontario and was in charge of the 18th Company, with headquarters in London, Ontario. He was responsible for selecting military positions and directing surveys for purposes of defence. In 1863, Hewett was posted to Pictou, N.S., and then to Halifax to work on the design and construction of new fortifications. In 1876, he opened the Royal Military College of Canada in Kingston, Ontario and served as its first Commandant until his resignation in 1886. He was responsible for drafting the curriculum and he chose the Royal Military College's motto, "Truth, Duty, Valour". He was appointed a Companion of the Order of St. Michael and St. George (CMG) in the 1883 Birthday Honours.

In 1864, he married Catherine Mary Biscoe (1842–1923). He died on June 3, 1897, in Woolwich, Kent, England.