Samsø municipality covers an area of 114.71 km² in the Kattegat sea, between the Danish mainland of Jutland and Zealand and comprise the island of Samsø and a number of small surrounding islands. The population is 3,747 (1 April 2014) and the mayor as of 1 January 2014 is Marcel Meijer, a member of the Socialdemokratiet (Social Democrats) political party. The municipal council is the town of Tranebjerg.
Since Samsø is an island municipality, Odder to the west in Jutland is the only neighbouring municipality. To the east is the strait of Samsø Bælt, separating Samsø from Zealand.