Mader came from a lower-middle-class family.^[1] Along with millions of other ethnic Germans, his family was forcibly relocated in 1945,^[1] ending up in the Soviet occupation zone of what remained of Germany, a region which was in the process of becoming the German Democratic Republic.

Mader attended business college, followed by an apprenticeship as a draper. Then he began to study in the fields of government and law, economics and journalism at the Universities of Berlin and Jena, the Institute of Internal Trade in Leipzig and the German Academy for Political and Legal Science in Potsdam-Babelsberg.

In 1955, he completed a Master of Business Travelers. A member of the SED, from 1958 to 59 he was deputy managing editor at a magazine. From 1960, he began working as a freelance writer. From 1962, he served as officer on special assignment with the code name "Faingold" for the Stasi. In 1965, he received his doctorate from the "Walter Ulbricht" Law Academy ("Deutsche Akademie für Staats- und Rechtswissenschaft "Walter Ulbricht"") at Potsdam-Babelsberg for a dissertation on "The secret services of the German Federal Republic and their subversive activities against the German Democratic Republic". In 1970, he received his habilitation (higher academic qualification) from the Humboldt University of Berlin, for a piece of work co-authored with Albert Charisius on the development, system and operation of the German secret service.

Mader's military and political writings covered the period of the Nazi era and the Cold War. His books have a circulation of several million^{[citation needed]}, including translations of some books into other languages.^[2] He was the author of the book Who's Who in the CIA.

• Paul Maddrell, "What we have discovered about the Cold War is what we already knew: Julius Mader and the Western secret services during the Cold War", Cold War History, Vol. 5, No. 2, May 2005, pp. 235–258, doi:10.1080/14682740500062127