St. George's Abbey was responsible for the foundation of the town of Isny, which was developed as a market at the end of the 12th century and received municipal status as early as 1235.

During the Reformation the town of Isny became Protestant and in 1534 the abbey church was attacked and its sacred images destroyed.

The abbey's economic situation only improved — temporarily — in the first third of the 17th century, which was brought to an end by a disastrous fire in 1631.

It was secularised in 1803, at the same time as the town of Isny was mediatised, when both became part of the territory of Count Otto Wilhelm von Quadt-Wykradt.

In the relatively brief period of prosperity that occurred in the first third of the 17th century much refurbishment and new building work took place, all of which were destroyed by the catastrophic fire in 1631.