The town has a history that can be traced back to the year 959, with the Montabaur fort castellum Humbacense.
The Archbishop-Elector of Trier, Dietrich von Wied, who came back from a Crusade in the Holy Land about 1217, had the humbacense castle newly built and named it Mons Tabor for its similarity to Mount Tabor in Israel, said to be the place of the Transfiguration of Jesus.
Out of this grew Montabaur.
In 1291, King Rudolf von Habsburg (1218–1291) granted Montabaur, as well as Welschbillig, Mayen, Bernkastel and Saarburg, town rights, so that the village became a town with its own coat of arms and a town wall.

In 1802 with the dissolution of the Archbishopric-Electorate of Trier the princes of Nassau took power in Montabaur and annexed it to the Duchy of Nassau in 1806.
With Prussia annexing Nassau in 1866 Montabaur became part of the Wiesbaden Region within the Province of Hesse-Nassau.
In 1945 the western Allies partitioned the northwestern part of the Wiesbaden Region with Montabaur and annexed it to the new German state of Rhineland-Palatinate.
The partitioned part of the Wiesbaden Region then formed the Montabaur Region (as of 1946) seated in Montabaur.
In 1968 the Montabaur Region, one of the originally five Regierungsbezirke of Rhineland-Palatinate, was dissolved and its territory annexed to the adjacent Koblenz Region.

Until early 2004, Montabaur was furthermore a Bundeswehr station with the Westerwaldkaserne, where the Raketenartilleriebataillon 350 (RakArtBtl 350) and, later, maintenance units were stationed.
The town has a history that can be traced back to the year 959, with the Montabaur fort castellum Humbacense. The Archbishop-Elector of Trier, Dietrich von Wied, who came back from a Crusade in the Holy Land about 1217, had the humbacense castle newly built and named it Mons Tabor for its similarity to Mount Tabor in Israel, said to be the place of the Transfiguration of Jesus. Out of this grew Montabaur. In 1291, King Rudolf von Habsburg (1218–1291) granted Montabaur, as well as Welschbillig, Mayen, Bernkastel and Saarburg, town rights, so that the village became a town with its own coat of arms and a town wall.
In 1802 with the dissolution of the Archbishopric-Electorate of Trier the princes of Nassau took power in Montabaur and annexed it to the Duchy of Nassau in 1806. With Prussia annexing Nassau in 1866 Montabaur became part of the Wiesbaden Region within the Province of Hesse-Nassau. In 1945 the western Allies partitioned the northwestern part of the Wiesbaden Region with Montabaur and annexed it to the new German state of Rhineland-Palatinate. The partitioned part of the Wiesbaden Region then formed the Montabaur Region (as of 1946) seated in Montabaur. In 1968 the Montabaur Region, one of the originally five Regierungsbezirke of Rhineland-Palatinate, was dissolved and its territory annexed to the adjacent Koblenz Region.
Until early 2004, Montabaur was furthermore a Bundeswehr station with the Westerwaldkaserne, where the Raketenartilleriebataillon 350 (RakArtBtl 350) and, later, maintenance units were stationed.
Montabaur