Following an adventurous youth in the American West, he graduated in medicine from McGill in 1862, studied abroad for 2 years and then began his practice in Sarnia, Canada West.
He was appointed superintendent of the Asylum for the Insane in Hamilton in 1876 and of the London asylum in 1877. He was a founder of the School of Medicine at University of Western Ontario. His theories on the causes and treatment of mental diseases and his advocacy of the "moral restraint" of the insane attracted widespread attention.
Bucke corresponded voluminously with Walt Whitman and became Whitman's official biographer and ultimately one of his literary executors. He found in Whitman's poetry a confirmation of his belief that the mystical experience, once the preserve of the few, will become accessible to the many. To this end he published his popular Cosmic Consciousness (1901), which attempts to demonstrate that man is on the verge of a psychic revolution. The book has enjoyed a vast readership. Bucke's papers are in the library at Western.