Since November 2008, Cornelia Quennet-Thielen has been State Secretary and Department Head at the Federal Ministry of Education and Research.

Previously, she was Director General at the Office of the Federal President beginning in 2004. First she led the Department of the Interior, followed by the Department of Legal and Administrative Services starting in 2006, while at the same time serving as Deputy Head at the Office of the Federal President. For many years, she worked at the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety: first as Personal Secretary to Federal Minister Klaus Töpfer beginning in 1987, then as the Head of Division for International Cooperation starting in 1990, and finally as Director for Policy Issues from 1999 on. Before this, she had been the Personal Secretary to Minister Klaus Töpfer at the Ministry for the Environment and Health in the Rhineland Palatinate region.

Cornelia Quennet-Thielen is a lawyer. In 1985 she served as state judge in Rhineland Palatinate after having passed her second state law examination in Mainz in late 1984. From 1976 to 1984, she studied law in Freiburg and Trier, after which she completed her practical traineeship. Cornelia Quennet-Thielen was a recipient of the German National Academic Foundation scholarship. In 2003 she returned to university to study abroad as a World Fellow at Yale University in the USA.

Cornelia Quennet-Thielen is a member and the president of the Administrative Commission of the German Council of Science and Humanities (Wissenschaftsrat), and a member of both the Leibniz Association Senate (Leibniz Gemeinschaft) and the Administrative Council of the Deutsches Museum in Munich. She is the Chair of the German-Polish Research Foundation Board of Trustees, and sits on the Board of Trustees for both the German Historical Museum and the Roland Berger Foundation. She represents the BMBF in the senate of both the Helmholtz Association (Helmholtz-Gemeinschaft) and the Max Planck Society (Max-Planck-Gesellschaft), as well as in the Board of Trustees of the Wissenschaftskolleg zu Berlin.

Cornelia Quennet-Thielen was born on 19 January 1957 in Freiburg. She is married.