Langenhahn is an Ortsgemeinde – a community belonging to a Verbandsgemeinde – in the Westerwaldkreis in Rhineland-Palatinate, Germany.

Langenhahn lies in the Upper Westerwald and belongs to the Verbandsgemeinde of Westerburg, a kind of collective municipality.

In 1386, Hölzenhausen followed as Holtershusen, in 1417 Hinterkirchen as Hinterkirche and 1593 Hintermühlen as “uff der Hintermuell im Braeschied”.

The six-spoked waterwheel stands for milling, which has been of great importance in the municipal area's history.

In Langenhahn there is a hard tennis court and a multi-purpose hall, which is used mainly for sporting activities.