Karl Falkenberg started his career in the European Commission negotiating on textiles. In 1990 he served as foreign policy advisor to EU President Jacques Delors, and from 1997 to 2000 was in charge of coordinating all WTO issues.
In 2001 he was appointed director in charge of sectoral trade policies and bilateral trade relations with North America, Japan, the Mediterranean area, and the African, Caribbean and Pacific countries. In 2002 he became director for free trade agreements, agricultural trade questions, and the ACP.
From 2005 to 2008 he coordinated all bilateral trade policies as deputy director-general. In January 2009 he became director-general for the environment.