Until 1 January 2007 Rudkøbing municipality was a municipality (Danish, kommune) in the former Funen County on the island of Langeland in south-central Denmark. The municipality included the islands of Strynø and Strynø Kalv, and covered an area of 63 km². It had a total population of 6,676 (2005). Its last mayor was Johan Norden, a member of the Social Democrats (Socialdemokraterne) political party. The main town and the site of its municipal council was the town of Rudkøbing. Part of the former municipality's southern border is defined by the Lindelse Cove (Lindelse Nor). A bridge connects the former municipality at the town of Rudkøbing over the islands of Siø and Tåsinge to the town of Svendborg on the island of Funen.
Ferry service connects the former municipality on the west side of the island at the town of Rudkøbing over the Little Belt to both the island of Strynø and to the town of Marstal on the island of Ærø; on the east side of the island there is ferry connection at the town of Spodsbjerg to the harbour on Lolland northwest of the town of Nakskov.
Rudkøbing municipality ceased to exist as the result of Kommunalreformen ("The Municipality Reform" of 2007). It was merged with existing Tranekær and Sydlangeland municipalities to form the new Langeland municipality. This created a municipality with an area of 290 km² and a total population of 14,223 (2005). The new municipality belongs to Region of Southern Denmark.