Having frequented the Gymnasium of Dresden, he studied law. From 1886 to 1899 he served on the administrative council of the district of Lüben, and then the council of Posen. In 1902 he became Minister of State for Anhalt and in 1901, Superior President of the province of Silesia. From 1903 to 1909 he was Minister-President of Anhalt, and from 1910 to 1914, Interior Minister of Prussia. After a conflict with his conservative colleagues, he resigned from the post (see Saverne Affair).
In 1914 Dallwitz, was chosen by Kaiser Wilhelm II as successor to Count Karl von Wedel as reichsstatthalter of Alsace-Lorraine. During this time, he attempted to join the Reichsland to Prussia. However, the outbreak of the First World War and the subsequent conflict between the populations of Alsace-Lorraine and Prussia led to the resignation of Dallwitz on 14 October 1918.