John H. Secondari was born in 1919 in Rome, Italy. In May 1924, he emigrated to the United States with his mother, Linda Secondari, on board the S.S. Providence, which sailed from Naples, Italy, and arrived at the Port of New York on June 4, whereupon they were immediately detained at Ellis Island as being in "excess of quota." They were finally released on June 11 and settled in Framington, Massachusetts. According to the passenger list, John Secondari was born in Bevagna, Umbria, Italy, not Rome. Secondari received a Bachelor of Arts from Fordham University in 1939 and a M.S. in Journalism from Columbia University in 1940. He joined the U.S. Army in 1941 and commanded a reconnaissance unit and a tank company in combat during World War II in France, Germany, and Austria. He was honorably discharged in 1946 with the rank of Captain.
Secondari married Rita Hume in 1948, but she died in a car accident in Mallorca, Spain. They had a son, John Gerry. In 1961, he married Helen Jean Rogers with whom he co-produced Saga of Western Man. They had a daughter, Linda Helen. He died of a heart attack at the age of 55 in New York City.