In 1975 Regling began work at the International Monetary Fund in Washington, D.C.. He spent his first two years as part of the IMF's Economist Program, specifically the Research and African Department, and the following three years as an economist in the Research Department. In 1980 Regling left and spent a year in the Economics Department of the Association of German Banks before being hired as an economist by the German Ministry of Finance, where he worked in the European Monetary Affairs Division until 1985. That year he returned to the IMF and worked both in Washington as well as in Jakarta, Indonesia. In 1991 Regling left the IMF once again and returned to the German Ministry of Finance, where he was named the Chief of the International Monetary Affairs Division. In 1993 he became the Deputy Director-General for International Monetary and Financial Relations and in 1995 the Director-General for European and International Financial Relations. In this capacity, he served as Chancellor Helmut Kohl’s representative to the IMF and the Group of Seven industrialised nations. While at the Ministry, he also held the roles of an alternate governor to the Asian Development Bank and the Inter-American Development Bank as well as on the supervisory board of Hermes Credit Insurance. He remained with the ministry until 1998. In 1999, Regling entered the private sector as the Managing Director of the Moore Capital Strategy Group in London, where his colleagues included David Lipton and Philipp Hildebrand. In addition to his role at Moore Capital, he served on the Financial Sector Review Group appointed by the Managing Director of the IMF, Horst Köhler, to provide the organization with an independent perspective on how it should organize its financial sector and capital markets work. Regling was appointed the Director General of the European Commission's Economic and Financial Affairs directorate in 2001 and remained there till June 2008. From 2008 to March 2009 he was part of the Issing Commission, which was formed by Chancellor Angela Merkel to advise the government on financial regulatory reform. He also became chairman of the Brussels-based KR Economics consultancy. On July 1, 2010 he became head of the European Financial Stability Facility.