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

Niederroßbach belongs to the Verbandsgemeinde of Rennerod, a kind of collective municipality.

Niederroßbach's neighbours are Oberroßbach, Fehl-Ritzhausen, Neustadt and Zehnhausen bei Rennerod.

Running right near the community are Bundesstraßen 54, linking Limburg an der Lahn with Siegen, and 255, leading from Montabaur to Herborn.

The nearest InterCityExpress stop is the railway station at Montabaur on the Cologne-Frankfurt high-speed rail line.