In 1225, Karlstadt had its first documentary mention. In 1236, the castle and the village of Karlburg were destroyed in the Rieneck Feud. In 1244, winegrowing in Karlstadt was mentioned for the first time. From 1277 comes the earliest evidence of the town seal. In 1304, the town fortifications were finished. The parish of Karlstadt was first named in 1339. In 1369 a hospital was founded. Between 1370 and 1515, radical remodelling work was being done on the first, Romanesque parish church to turn it into a Gothic hall church. About 1400, Karlstadt became for a short time the seat of an episcopal mint. The former "Oberamt" of the Princely Electorate ("Hochstift") of Würzburg was, after Secularization, in Bavaria's favour, passed in 1805 to Grand Duke Ferdinando III of Tuscany to form the Grand Duchy of Würzburg, and passed with this to the Kingdom of Bavaria.