The Coat of arms of the Grand Duchy of Saxe-Weimar-Eisenach was created in 1815 when the area was raised to the title of Grand Duchy, and ended in 1918 with the transition of Saxe-Weimar-Eisenach into the new state of Thuringia. The full grand ducal style was Grand Duke of Saxe-Weimar-Eisenach, Landgrave in Thuringia, Margrave of Meissen, Princely Count of Henneberg, Lord of Blankenhayn, Neustadt and Tautenburg, and this is represented in the arms:
| Grand Duchy of Saxe-Weimar-Eisenach | |
|---|---|
 | |
| Crest | Silver helm; crown |
| Shield | Quarterly: the striped lion of Thuringia; the lion of the Margraviate of Meissen; the arms of the County of Henneberg and Estate of Arnshaugk; Lordship of Blankenhain and the arms of the Tautenburg estate. Above all an escutcheon for Saxony |
| Supporters | Two golden lions |
| Motto | VIGILANDO ASCENDIMUS ("We rise by being vigilant") |
| Use | Ended 1918 |
It was used on the Grand Ducal Standard c.1862 - c.1878.[1]