Isenburg-Neumagen was the name of a state of the Holy Roman Empire, seated in Neumagen-Dhron in modern Rhineland-Palatinate, Germany.
Isenburg-Neumagen was created on the partition of Lower Isenburg in 1502. There were only two counts of Isenburg-Neumagen, and at their extinction it passed to the Counts of Sayn-Homburg.