Coleman was born in Richfield Springs, New York, and later moved to Kentucky to become an educator. He received a law degree from the University of Louisville Law School in 1849. Coleman then moved to Missouri and went into farming. In 1855 he founded the Valley Farmer newspaper. As a result of his publication, Coleman became a prominent figure in Missouri farming circles, which set the path for a political career in the Missouri House of Representatives. The publication of Coleman’s newspaper was interrupted by the American Civil War, but three years after the war he founded the Coleman’s Rural World. His political career continued when he was appointed as Lieutenant Governor of Missouri from 1875 to 1877. During his tenure he campaigned for the creation of the United States Department of Agriculture under the administration of President Grover Cleveland, of which he served as its inaugural Secretary for the remainder of Cleveland’s term. His position as Secretary of Agriculture was never confirmed by the Senate.
He was a member of the Freemasons.