Ernest Greenwood (November 25, 1884 – June 15, 1955) was an American schoolteacher and principal.

Deciding on a career in education, Greenwood attended City College of New York and Columbia University, and then taught in the Schenectady public schools from 1914 to 1916.

During World War I, Greenwood was a member of committee on Census and Inventory of Military Resources and from 1920 to 1922 he was supervisor of the Federal Board of Vocational Education.

During World War II, Greenwood served on Islip's Rationing Board.

In 1950, Greenwood was elected to the Eighty-second Congress as a Democrat, defeating Republican incumbent W. Kingsland Macy.