Its mayor as of 1 January 2014 is Erik Lauritzen, a member of the Social Democratic party.

Sønderborg's municipal council consists of 31 members, elected every four years.

The former Sønderborg municipality covered an area of 54 km2 (21 sq mi), and had a population of 30,555 (2005).

The municipality is home to two of the major industrial companies in Denmark: Danfoss and Linak.

Sønderborg Municipality is home to the only officially recognised ethno-linguistic minority of Denmark proper, the North Schleswig Germans.