St. Johann is situated in the Leukental, which extends from Jochberg to the Streichen close to the Bavarian border. This region was already settled in the 4th century BC by a Celtic tribe, the Ambisontiers, who pursued copper mining in the surrounding mountains.
In 15 BC the Romans conquered the Eastern Alpine region and the Leukental became part of the Roman province of Noricum. Following the downfall of the West Roman Empire in 476 AD the region went to the Duchy of Bavaria in the 7th century in the wake of the European migrations and as result of the settlement of the Germanic tribe of the Bavarii.
In the following centuries the nobles of the House of Liuchinger, after whom the Leukental is named, established a county in the valley. The Liuchingers lived at Leukenstein Castle, which is located at the foot of the Niederkaiser. The exact site of the castle, which was also the judicial seat for the county, is no longer known today, but is recalled by the farm name of Burgwiesen ("castle meadows"). Following the extinction of the Liuchingers around 1170, their county ended up in the hands of the Falkensteins, but this noble family also died out after just 70 years and the county in the Leukental was subsequently ruled by officials representing the Bavarian dukes.
In the 8th century (probably before 738), the missionaries built a Catholic church in the region of St. Johann, which was dedicated to St. John the Evangelist and who gave St. Johann its name. The church of St. Johannes was first mentioned in a document in the year 1150.
In 1446, the bishops of Chiemsee were given the responsibility of the parish of St. Johann, from which time onwards it became their summer residence.
The opening of the copper and silver mines in 1540 increased the wealth of St. Johann. The mines were located in the small hills, known as Rerobichl close to Oberndorf, which belonged to St. Johann. In the 17th century the Heilig-Geist-Schacht ("Holy Ghost
