John Ely (October 8, 1774 – August 20, 1849) was an American physician and politician who served one term as a U.S. Representative from New York from 1839 to 1841.
Born in Saybrook, Connecticut, Ely completed preparatory studies. He studied medicine, and practiced in Coxsackie, New York. He served as member of the State assembly in 1806 and 1812. He was one of the organizers of the New York State and Greene County Medical Societies in 1807 and also of the Albany Female Academy.
Ely was elected as a Democrat to the Twenty-sixth Congress (March 4, 1839 – March 3, 1841).
He resumed the practice of medicine. He died in Coxsackie, New York, August 20, 1849. He was interred in Old Coxsackie Cemetery.