Haderslev (German: Hadersleben) is a town and municipality on the east coast of the Jutland peninsula in the Region of Southern Denmark. It includes the island of Årø as well as several other smaller islands in the Little Belt. The municipality covers 701.98 km2 (271 sq mi) and has a population of 56,414 (2008). Its mayor is Jens Christian Gjesing, representing the Social Democratic Party. Due to Kommunalreformen ("The Municipal Reform" of 2007), Haderslev municipality was merged on January 1 of that year with the former municipalities of Gram and Vojens, as well as Bjerning, Hjerndrup, and Fjelstrup parishes of Christiansfeld Municipality and Bevtoft parish of Nørre Rangstrup Municipality.
The waters of Haderslev Fjord cut into the municipality from the Little Belt, dividing the city north-to-south, becoming Haderslev Dam west of the city centre. Årø Strait (Årøsund) separates the bulk of the municipality from the island of Årø, and the two are connected by ferry service between the town of Årøsund on the mainland and the town of Årø on the island.
The main town and the site of the municipal council is the city of Haderslev.
Haderslev Municipality is home to the only officially recognised ethno-linguistic minority of Denmark proper, the North Schleswig Germans. This minority makes up about 6% of the total population of the municipalities of Aabenraa/Apenrade, Haderslev/Hadersleben, Sønderborg/Sonderburg and Tønder/Tondern. In these four municipalities, the German minority enjoys certain linguistic rights in accordance with the European Charter for Regional or Minority Languages.
Haderslev's municipal council consists of 31 members, elected every four years. The municipal council has nine political committees. 
Below are the municipal councils elected since the Municipal Reform of 2007.
|2005||13||1||1||1||2||13||31||73.3%||Hans Peter Geil (V)|
|2009||14||1||2||2||1||11||69.6%||Jens Christian Gjesing (A)|
|2013||9||2||1||1||4||1||11||2||74.1%||Hans Peter Geil (V)|
|Data from Kmdvalg.dk 2005, 2009, 2013 and 2017|