Undenheim is an Ortsgemeinde, or municipality, located in the Mainz-Bingen district of Rhineland-Palatinate, Germany. It functions as a member of the Verbandsgemeinde Rhein-Selz, which is a type of collective municipality.
The administrative seat for the Verbandsgemeinde Rhein-Selz is situated in Oppenheim. Undenheim serves as one of the constituent local communities within this regional administrative structure.