Between 1985 and 1993, Ould-Abdallah worked as adviser on energy, including renewable energies and African issues, to the United Nations Secretary-General. From 1993 to 1995, he was Secretary General Boutros Boutros-Ghali's Special Representative in Burundi, during the first part of the Burundi Civil War. Between 1996 and 2002, he served as the Executive Secretary of the Global Coalition for Africa, a Washington D.C. based intergovernmental forum dedicated to African issues. In 2002, Secretary General Kofi Annan appointed him Special Representative for West Africa at the head of the United Nations Office for West Africa.