Egeland earned a bachelor's degree in political science from the University of Oslo (1982) and studied as a Fulbright scholar at the University of California, Berkeley (1982–83). He served as a fellow at the Truman Institute for the Advancement of Peace in Jerusalem before returning to the University of Oslo to earn a master's degree in political science (1985). Although he worked briefly as a radio and television reporter for the Norwegian Broadcasting Corporation, most of his career was spent with humanitarian and government agencies. Egeland was the chair of Amnesty International in Norway (1979–81) and a vice-chair of the International Executive Committee of Amnesty International (1980–86). He also served as secretary-general of the International Department of the Norwegian Red Cross (1988–90). From 1992 to 1997, as state secretary in the Norwegian Ministry of Foreign Affairs, he developed preparedness systems that supplied relief workers to international organizations. During this period he was involved in a number of diplomatic efforts, acting as a liaison between Israel and the Palestine Liberation Organization in talks that resulted in the Oslo Accords (1993) and as a liaison in talks between the Guatemalan government and guerrillas that led to a peace agreement (1997). Egeland represented Norway in negotiating the Ottawa Treaty (1997) to ban land mines. From 1999 to 2001 he was a special adviser on Colombia to UN Secretary-General Kofi Annan (Annan, Kofi), who on June 6, 2003, appointed him undersecretary-general for humanitarian affairs and emergency relief coordinator.

Egeland took an active role in attempting to solve political and military crises, including threats in the Democratic Republic of the Congo, in the Darfur region of The Sudan, and in Uganda. His office was also involved in relief efforts following two major natural disasters: the Indian Ocean tsunami of 2004 and Hurricane Katrina, which in 2005 struck parts of the U.S. Gulf Coast. He characterized the initial response of Western countries to the tsunami as “stingy,” shaming some countries into increasing their aid, and he was a persistent critic of the lack of preparedness worldwide against national disasters and emergencies. In 2006 Time magazine named him one of the 100 “people who shape our world.” Egeland stepped down from his post in December 2006 but remained with the UN as a special envoy for conflict resolution. In September 2007 he was named director of the Norwegian Institute of International Affairs.