Cook was born in Camberwell, London and educated at Mill Hill School, as were his two brothers Frank and Thomas. He entered the family travel business, and developed its banking operations. In 1928, along with his brother Frank, he sold his business interest in the family firm to the Compagnie Internationale des Wagons-Lits.
Following the sale Cook retired to Bath, and devoted himself to his art collection and the acquisition of country estates. He accumulated a large collection of fine and decorative art, which on his death became the largest bequest ever left to the National Arts Collection Fund. In 1931 he acquired Montacute House in Somerset and the Bath Assembly Rooms for the Society for the Protection of Ancient Buildings.
He became a major benefactor of the National Trust, and encouraged the Trust to acquire historic country houses and estates. Montacute House and the Assembly Rooms were transferred to the National Trust. Cook acquired a total of seventeen estates, of which Bradenham, Buscot and Coleshill passed to the National Trust.
- E. J. T. Collins (2004). "Cook, Ernest Edward (1865–1955)". Oxford Dictionary of National Biography, Oxford University Press. Retrieved 2011-07-08.
- Collins, E. J. T. and Giles, A. K. (1989). Innovation and Conservation: Ernest Edward Cook and his Country Estates. University of Reading. ISBN 978-0-7049-0708-9.