Dr. h. c. Karl Blecha founded the Insititute for Empirical Social Research (Institut für Empirische Sozialforschung-IFES) in Vienna in 1963 and lead it until 1975. Under his leadership, it became one of the most established reasearch centres for applied social sciences in the German speaking region. From December, 1975 to May, 1981, Karl Blecha was the Secretary General of the SPÖ (Austrian Social Party) and in 1981, he was elected as the Vice Chairman of the party and repeated re-elected in this function. From 1964 to 1989, he was on the board of the Lower Austrian SPÖ, and from 1970 to 1983 he was a parliament member.
Karl Blecha was the Secretary of the Social Sciences Research Association (Sozialwissenschaftliche Studiengesellschaft), Vice President of the Austrian Society for Sociology (Österreichische Gesellschaft für Soziologie) and is still the President of the Austrian Society for the Promotion of Research (Österreichische Gesellschaft zur Förderung der Forschung).
Karl Blecha was appointed as the Interior Minister in 1983. In this position he worked for four coalition governments until 1989.
Karl Blecha has been awarded the Great Golden Medal of Honour of the Order for Services to the Republic of Austria.