John Harmon may refer to:

• John Harmon (actor) (1905–1985), American actor
• John Harmon (attorney) (born 1944), United States Assistant Attorney General under President Jimmy Carter
• John Harmon (coach), Boston University basketball and football coach
• John Harmon (character), a character in Our Mutual Friend
• John Harmon (Wisconsin politician) (1845–1921), American lumberman and politician.
• John H. Harmon (1819–1888), mayor of Detroit and publisher of the Detroit Free Press
• John T. W. Harmon Liberian-American bishop of the Episcopal Diocese of Arkansas