He was born in Pontotoc, Mississippi to William Holmes Cochran and Emma Grace Cochran, a principal and teacher, respectively. His family settled in Hinds County, Mississippi in 1946 after a few moves around the northern part of the state.
Cochran received a B.A. degree from the University of Mississippi with a major in psychology and a minor in political science in 1959. After a time in the United States Navy (1959-1961), he attended the University of Mississippi School of Law and graduated in 1965. He then practiced law for seven years. He was elected three times to the U.S. House of Representatives (1972, 1974, 1976) and then was elected to the United States Senate in 1978, succeeding James Eastland. The senior senator from Mississippi, Cochran is currently Chairman of the Agriculture, Nutrition and Forestry Committee. He is next in line to be Chairman of the Appropriations Committee in the next Congress. He was reelected in 1984, 1990, 1996, and with almost no opposition to his fifth term in 2002.