The castle was founded around 1080 by Hartnidus of Ort, and improvements continued to be made into the thirteenth century - for example by Hartnidus V in 1244. In 1344 the brothers Friedrich and Reinprecht I of Wallsee purchased the castle, which became Friedrich’s sole possession on January 25, 1350. The castle remained in the possession of the Wallsee family until 1483, when Schloss Ort passed to Frederick III, Holy Roman Emperor.
From 1484 to 1491, the castle was governed by Gotthard von Starhenberg, the Governor of Upper Austria. In 1492, Bernhard of Starhenberg and later his descendants ruled the castle until 1584. In 1588, the castle was purchased by Weikhard Freiherr of Pollheim, but he sold the castle on April 6, 1595 to the city of Gmunden. However, Gmunden sold the castle to Rudolf II that same year. The castle then passed to other owners before finally being acquired by Leopold I, Holy Roman Emperor.
In 1876, the castle was acquired by Archduke John Salvator of Austria (John of Tuscany) (1852 – ca. 1911), but on October 6, 1889, he renounced his title and connections to the Habsburg imperial house and changed his name to Johann Orth, the tenth and last child of Grand Duke Leopold II of Tuscany and Maria Antonietta of the Two Sicilies departing for South America in 1890 with his morganatic wife on his own ship, the St. Margaret. Johann Nepomuk Salvator was presumed lost at sea in 1890, and declared dead in 1911, but his actual date of death is unknown.
The castle was not well maintained between 1919 and 1973.
At present the castle is being used for a study center of the Federal Ministry for Land and Forestry (Bundesministeriums für Land- und Forstwirtschaft). On January 5, 1995, the castle was officially acquired by the city of Gmunden. In 1996, it began to be used as a location for the TV series Schlosshotel Orth.