1970 - Halldór earned a bachelor's degree from the Co-operative College of Iceland, and became a certified public accountant.
1973 - He later completed graduate commerce studies at the Universities of Bergen and Copenhagen, and worked as a lecturer at the University of Iceland.
1974 - He represented the East constituency as a member of the Alþingi.
1983 - He has served in a large number of ministerial portfolios, namely as Minister for Fisheries, Minister of Justice.
1985 - Minister for Nordic Co-operation.
1988 - Ecclesiastical Affairs.
1995 - Minister of Foreign Affairs.
2004 - He took over as Prime Minister on the 15th of September, from the Independence Party leader, Davíð Oddsson, who had held the office for a record thirteen years.
2006 - In June, following poor results in municipal elections, Halldór announced his resignation as Prime Minister and stated that he intended to step down as leader of the Progressive Party in August 2006.
- Halldór Ásgrímsson's successor as Progressive party leader was elected Jón Sigurðsson, minister of Industry and Commerce, at the party's convention in August.
- On the 31st of October, Halldór was chosen as the new secretary general for the Nordic Council of Ministers.