A native of Brooklyn, he attended New York City public schools, graduating from the Boys' High School (now Boys and Girls High School) in 1961. Nofi attended Fordham University, earning a bachelor's (1965) and a master's (1967), and then received a Ph.D. in Military History from the City University of New York (1991).
From 1965 through 1995, Nofi was a teacher and later administrator in the New York City public schools. Working primarily in alternative programs, such as the Harlem Preparatory School, Park East High School, and Unity High School at the Door, he retired as an assistant principal in 1995.
During this period he also built a parallel career as an independent historian, defense analyst, and wargame designer, working primarily with James F. Dunnigan, Redmond A. Simonsen, and David C. Isby at Simulations Publications (SPI). As research director for SPI and associate editor of the military historical simulations journal Strategy and Tactics for over a decade (1969–1982), he produced numerous articles and a number of wargames. Nofi also designed the strategic-level Roman Empire wargame Imperium Romanum (1979) for West End Games.
In addition to work for SPI, Nofi has authored, co-authored, or edited over 30 books on a wide variety of topics. Among his collaborators are Dunnigan, Bela Kiraly, Richard L. DiNardo, Kathleen Broome Williams, and others.
In 1999 Nofi became a research analyst with the Center for Naval Analyses (CNA), in Alexandria, Virginia, where he worked with game theorist Peter P. Perla. Nofi was the CNA field representative to the Chief of Naval Operations Strategic Studies Group, in Newport, Rhode Island, from 2001 until mid-2005, before returning to CNA. While at CNA he wrote "Recent Trends in Thinking About Warfare" and several other analytical papers. He retired from CNA at the end of 2006.
Nofi has lectured at the University of Paris-Sorbonne, the Smithsonian Institution, the Library and Archives Canada, the Admiral Nimitz State Historic Site (home of the National Museum of the Pacific War), the Air War College, the Command and Staff College of the Marine Corps University, a number of other colleges and universities, and numerous Civil War Round Tables and local historical societies.
For many years an Associate Fellow of the U.S. Civil War Center, a Director of the New York Military Affairs Symposium since its formation, a member of the Society for Military History and a number of other military and historical societies, Nofi is also a founding member of the American Italian Historical Association
From 1997 to 2013, Nofi contributed a regular column to North & South magazine. In 1998, he became a contributing editor to StrategyPage, for which he writes a regular column.
In 2011 Nofi's book To Train the Fleet for War: The U.S. Navy's Fleet Problems, 1923-1940 (see review) was awarded the John Lyman Book Award in Navy History by the North American Society for Oceanic History and given "Honorable Mention" by The New York Chapter of the Navy League of the United States for its Theodore and Franklin D. Roosevelt Prize in Naval History.The Great War: 1914-1918. Mission Viejo: One Small Step, 2015.
Victory at Sea, with James F. Dunnigan. 360-Pacific, 1994.
The Hundred Years' War,  with James F. Dunnigan. StrategyWorld, 1992.
Man-at-Arms, with James F. Dunnigan. Cambria, Ca: 3W Inc, 1990.
Imperium Romanum II. New York: West End Games, 1985.
Sicily: Operation Husky. New York: Rand Games, 1981.
Knights & Knaves: the Game of Medieval Skullduggery. New York: Nimrod Games, 1979.
Imperium Romanum. New York: West End Games, 1979.
The Great War. New York: West End Games, 1978.
Salerno. New York: West End Games, 1978.
Caporetto. New York: Simulations Publications, 1978.
Wellington in the Peninsula. New York: Rand Games, 1975.
Vicksburg: The War for the West. New York: Rand Games, 1975.
Centurion. New York: Simulations Publications, 1971.
Renaissance of Infantry. New York: Simulations Publications, 1970.