He served in the United States Army during World War II.
In 1970, President of the United States Richard Nixon nominated Buffum as United States Ambassador to Lebanon and Buffum held this post until 1974.
Nixon then nominated Buffum as Assistant Secretary of State for International Organization Affairs; Buffum held this office from February 4, 1974, until December 18, 1975.
In the later 1970s, Buffum was Under-Secretary-General of the United Nations for Political and General Assembly Affairs.
Buffum died on April 13, 2012, at his house on the island of Hawaii.