The line is mainly worked by regional trains, including diesel multiples of the DreiLänderBahn, except for the IC 34, which runs between Frankfurt and Siegen, stopping in Dillenburg.

The southern part is the south-western section of the Deutz–Gießen line built by the Cologne-Minden Railway Company and completed originally as a single-track in January 1862 from Köln-Deutz to Gießen.

The population of the rural areas along the Dill river was initially largely hostile to the construction of the railway, although it contributed to the prosperity of the region.

The central section of the Deutz–Giessen line ran from Betzdorf via Burbach and Würgendorf to Haiger, the route of the current Heller Valley Railway.

Due to the difficult terrain, construction of a direct connection from Siegen to the Dill line was too expensive at the time.