Born November 27, 1947, in Münster, Lenzen studied education, philosophy, and German, English, and Dutch languages and literatures in Münster. He earned his doctorate in 1973 and worked from 1973 to 1975 in the educational research department at the Ministry of Culture of the state of North Rhine-Westphalia. From 1975 to 1977, he worked as a professor of education at Westfälische Wilhelms-Universität (University of Münster).

Starting in 1978, Lenzen was a professor of educational philosophy at Freie Universität Berlin. In 1990, he became a member of the Board of the German Society for the Study of Education (Deutsche Gesellschaft für Erziehungswissenschaft), and served as that body’s chairman from 1994 to 1998. Between 1986 and 1994, Lenzen served as a visiting professor at Stanford University, Columbia University, and the Universities of Tokyo, Hiroshima, and Nagoya. He headed a number of projects in the field of education research for various clients based in both the public and private sectors. Lenzen has been the chairman of the Aktionsrat Bildung (Educational Action Council) since 2005.

From 1999 to 2010, Lenzen was a member of the Executive Board of Freie Universität Berlin, first as executive vice president and then, from 2003 to 2010, as president. Lenzen left his office at Freie Universität in 2010 to become the president of the University of Hamburg.

In May 2007, Lenzen was elected vice president of the German Rectors’ Conference (Hochschulrektorenkonferenz). German President Horst Köhler awarded him the Cross of the Order of Merit of the Federal Republic of Germany (Verdienstkreuz am Bande des Verdienstordens der Bundesrepublik Deutschland) in 2005.