Peter van Walsum was formerly the United Nations Secretary-General's Personal Envoy for Western Sahara. He was appointed to the position by United Nations Secretary-General Kofi Annan in July 2005 and left the position in September 2008 when his mandate expired.

Previously, he was the Netherlands' Permanent Representative to the United Nations. He also served as his country's representative on the Security Council in 1999 and Chairman of the Iraq Sanctions Committee in 2000.

He obtained his law degree from the University of Utrecht in 1959. He served in the military from 1960 to 1962 and then joined the Civil Emergency Planning in the Ministry of General Affairs from 1962 to 1963.

Later on, he served at the Netherland's Ministry of Foreign Affairs, where he was posted to various positions in his nearly four decades career, including the Permanent Mission to the North Atlantic Treaty Organization (NATO) in Paris, the Embassy in Bucharest, the Permanent Mission to the United Nations in New York, the Embassy in both New Delhi and London, and the Permanent Mission to the European Commission in Brussels.