He studied at Brooklyn College 1951–53 and went on to be a photojournalist, filmmaker, United Hias Service, NYC 1953–57. As a writer, he began at the American Cancer Society in New York (1958–63) and then at the United Nations in New York and Rome (1963–64). He was a freelance writer from 1964 until his death.
He fulfilled academic roles at numerous institutions, including being Visiting Professor of Investigative Journalism at the University of California, Santa Cruz (1986–92). Awarded an ongoing Guggenheim Fellowship in 1970, he has also been a fellow of Adlai E. Stevenson College; University of California during 1986 to 1992. He became a grantee of the American Council of Learned Societies in 1971; and a recipient of the Laceno d'Oro (best screenplay) award at the Neorealist Film Festival in Avellino, Italy (1983).
Katz was involved in a criminal-libel in Italy over the contents of his book Death in Rome, in which he was charged with "defaming the memory of the Pope" Pius XII regarding the Ardeatine Massacre of 335 Italians, including 70 Jews, at the Ardeatine Caves in 1944. The case ended with the charges being dismissed in 1980 by Italy's highest court. The suit had been issued by the Pope's family. The book was made into the 1973 film Massacre in Rome.
- Death in Rome, New York: Macmillan Publishers, 1967.
- Black Sabbath: A Journey through a Crime against Humanity, Macmillan, 1969.
- The Fall of the House of Savoy, Macmillan, 1971.
- A Giant in the Earth, Stein & Day, 1973.
- Days of Wrath: The Ordeal of Aldo Moro, the Kidnapping, the Execution, the Aftermath, Doubleday, 1980. (Pulitzer Prize nomination 1981)
- Il caso Moro (with G. Ferrara and A. Balducci), Pironti, 1987.
- Love is Colder than Death: The Life and Times of Rainer Werner Fassbinder, Random House, 1987.
- Naked by the Window: The Fatal Marriage of Carl Andre and Ana Mendieta, Atlantic Monthly Press, 1990.
- Dossier Priebke, Rizzoli, 1997.
- The Battle for Rome: the Germans, the Allies, the Partisans and the Pope, September 1943-June 1944, Simon & Schuster, 2003.
- The Cassandra Crossing, Ballantine, 1976.
- Ziggurat, Houghton, 1977.
- The Spoils of Ararat, Houghton, 1978.
- Massacre in Rome (1973) (book "Death in Rome") (screenplay)
- The Cassandra Crossing (1976) (screenplay) (story)
- The Salamander (1981) (writer)
- La pelle (1981) (screenplay)
- Kamikaze 1989 (1982) (writer)
- Dolce e selvaggio (1983) (English dialogue)
- Il Caso Moro (1986) (book Days of Wrath) (screenplay)
- Il cugino americano (1986) (story)
- Hotel Colonial (1987) (writer)
- La Peste (1992) (narration)
- The Contractor (2007) (V) (story)
- Washington Post reports death retrieved 21st October 2010
- "Robert Katz". All Things Katz. Retrieved 2008-05-26.
- (Italian) "Official site of Laceno d'oro". Retrieved December 18, 2012."Official site of Laceno d'oro". Retrieved December 18, 2012.
- "Avellino Neorealism Film Festival". Retrieved December 18, 2012.
- "Where there's holy smoke there's fire," 24 September 1999, Times Higher Education, retrieved 1 July 2009.
- "The End of the Pius Wars," Joseph Bottum, First Things Magazine, April 2004, retrieved 1 July 2006.
- Bruce Webber (October 22, 2010). "Robert Katz, Who Wrote About Nazi Massacre in Italy, Dies at 77". The New York Times. Retrieved 22 October 2010.