He obtained an honorary doctorate from the Åbo Akademi, Finland in, 1988, from the University of Copenhagen in 1990.
Olsen has started his career as journalist and reporter for various Norwegian newspapers from 1958 to 1963.
He started his academic career as research assistant at the Institute of Political Science of the University of Oslo in 1965.
[5] Olsen is one of the developers of the systemic-anarchic perspective of organizational decision-making known as the Garbage Can Model.
[6] In 2003 he received an honorary doctorate by the Erasmus University Rotterdam, department of Public Administration.