Derek Chollet served as the Chief of Staff to Secretary of Defense Lloyd J. Austin, III. He was responsible for leading the Secretary of Defense's executive staff and providing counsel and advice to the Secretary on all matters concerning the Department.

From January 2021 to July 2024, he was the Counselor of the U.S. Department of State, where he served at the rank of Under Secretary as a senior policy advisor to Secretary of State Antony Blinken on a wide range of issues and conducted special diplomatic assignments as directed by the Secretary.

From 2012-2015, Mr. Chollet was the U.S. Assistant Secretary of Defense for International Security Affairs, where he managed U.S. defense policy toward Europe, the Middle East, Africa, and the Western Hemisphere. Prior to joining the Pentagon, Chollet served at the White House as Special Assistant to the President and Senior Director for Strategic Planning on the National Security Council (NSC) staff.  From 2009 to 2011, he was the Principal Deputy Director of the State Department's Policy Planning Staff.  He served on the 2020 Biden-Harris State Department transition team as well as the 2008 Obama-Biden NSC transition team.

During the Clinton Administration, Chollet served as Chief Speechwriter for UN Ambassador Richard Holbrooke, and as Special Adviser to Deputy Secretary of State Strobe Talbott.  Earlier in his career he assisted former Secretaries of State James A. Baker III and Warren Christopher, as well as Holbrooke and Talbott, with the research and writing of their memoirs.

Outside of government, Mr. Chollet has held a variety of positions at leading research institutions.  From 2016-2020 he served as Executive Vice President and Senior Advisor for Security and Defense Policy at The German Marshall Fund of the United States (GMF), and as a visiting fellow at the University of Pennsylvania's Perry World House. He has also been a fellow at the Center for a New American Security, the Center for Strategic and International Studies, the Brookings Institution, the Kissinger Center for Global Affairs at Johns Hopkins/SAIS, and the American Academy in Berlin. He is the author, coauthor, or coeditor of eight books on U.S. foreign policy, and is the recipient of numerous honors and awards, including the U.S. Department of Defense Medal for Distinguished Public Service, the U.S. Secretary of Defense Medal for Outstanding Public Service, and the U.S. State Department Superior Honor Award.  A graduate of Cornell, he was raised in Lincoln, Nebraska.