Woldemar Carl von Daehn (20 February 1838 in Sippola – 28 December 1900) was a Finnish politician.

He served as an officer in the Imperial Russian Army for 20 years, but returned to Finland in 1882 when he was appointed the governor of the Vyborg province.

In 1885 he was promoted chief of then Ministry of the Interior, also becoming a member of the Senate of Finland, where he often had heated debates with Leo Mechelin.

He faced numerous difficult conflicts and uproar regarding what were seen as reductions of Finnish autonomy in the 1890s, such as the 1890 Postal Manifest [fi] by tsar Alexander III and many others such as regarding criminal law and the entire state system of the Grand Duchy of Finland.

He played a large part in negotiations concerning Finland with tsars Alexander III and Nicholas II.