Dietmar Nickel was born on 26 February 1947 in Hamburg, Germany. He studied law at the Universities of Hamburg and Lausanne. After passing his first state examination in law in 1973, he worked as a Research Assistant at the Faculty of Law at the University of Hamburg. He completed his second state examination in law in 1976 and earned his PhD (Dr. iur.) from the University of Hamburg in 1978. From 1976 to 1978, he was a lecturer at the European University Institute in Florence.
From 1978 until his retirement in 2010, Nickel served as a civil servant in various roles at the European Parliament. He was Deputy Secretary General of the Socialist Group in the European Parliament and held key leadership roles: from 1999 to 2003 as Director General for Committees and Delegations, and from 2004 to 2010 as Director General for External Policies of the European Union.
After retiring from the European Parliament, Dietmar Nickel became a Non-resident Senior Fellow in the Foreign Policy Research Division at the German Institute for International and Security Affairs (SWP) in February 2011. He is the author of numerous publications on institutional matters.His research focuses on European integration and development policy. He also lectures on the constitutional politics of the European Union at the Europa-Kolleg Hamburg.