Conniff was born in Danbury, Connecticut. His first newspaper job was as a copyboy with the Danbury News-Times. He went to college at the University of Virginia, and after covering sports for one year in Danbury, joined Hearst Newspapers in New York. He was also a combat reporter during World War II in Africa and Europe, and covered the Korean War in 1950–51.[1] In 1958 he became general director of the Hearst Headline Service, which provided news features, and contributed a Washington column. In New York he later wrote the "Conniff's Corner" column.[1] While Hearst would introduce Conniff as their "house Democrat," Conniff also supported Joseph McCarthy, as Hearst Newspapers were a McCarthy supporter. He unsuccessfully challenged Republican Congressman Ogden Reid of New York's 26th congressional district in the 1964 election.[1][3][4]
Conniff was editor of Hearst Newspapers's World Journal Tribune of New York from 1966 to 1967, when the newspaper ceased publication. He was also national editor of Hearst Newspapers.[6] He had a stroke shortly after the close of the World Journal Tribune from which he partly recovered.[2]