John Nathan Mayo (December 1876 – April 14, 1960) was an American agricultural and corrections administrator who served as the Florida Commissioner of Agriculture from 1923 to 1960. He was Florida's longest serving Agricultural Commissioner. Mayo was said to run the most powerful political organization in the state. During his tenure, Mayo worked to increase the quality of Florida agricultural produce and promote the state nationally. He also stopped a state government attempt in the 1920's to drain the Everglades.