The Duchy of Saxe-Marksuhl was one of the Saxon Duchies held by the Ernestine line of the Wettin Dynasty.

Established in 1662 for John George I, third son of Wilhelm, Duke of Saxe-Weimar.

Originally John George was supposed to share Saxe-Eisenach with his older brother, Adolf William.

[1] Johann Georg finally accepted the receipt of an income from the duchy of Saxe-Eisenach and made his residence in the small town of Marksuhl.

Saxe-Marksuhl was reincorporated into Saxe-Eisenach on the accession of John George to the Duchy of Saxe-Eisenach upon his nephew's death in 1671.