Ransbach-Baumbach (German pronunciation: [ˈʁansbax ˈbaʊmbax]) is a town in the Westerwaldkreis in Rhineland-Palatinate, Germany. Ransbach-Baumbach is the seat of the Verbandsgemeinde of Ransbach-Baumbach, a kind of collective municipality.

The community lies in the Westerwald about 10 km northwest of Montabaur, and 15 km northeast of Koblenz.

In 1330, the parish of Ransbach had its first documentary mention. Already in 959, however, the Montabaurer Zehntbeschreibung (a “description of tithes”), speaks of the vanished community of Desper (Dedinsburg) near Ransbach. In 1373, the name Babenbach for Baumbach crops up. In 1969, Ransbach and Baumbach were merged into one community. In 1971, in the course of municipal restructuring, the Verbandsgemeinde of Ransbach-Baumbach was founded. In 1975, Ransbach-Baumbach was granted town rights.

Ransbach-Baumbach lies in the heart of the Kannenbäckerland, a small region known for its ceramics industry.

The district Ransbach was located on the Engers-Au railway, the section between Engers and Siershahn is currently out of service.

Ransbach-Baumbach is served by the local bus lines 425, 427, 461, 467, 485 and 964 and located in the area of the transport association Verkehrsverbund Rhein-Mosel (VRM), fare zone 415.

Since 1676 the Fohr Brewery has been in Ransbach-Baumbach.