The village is situated on the south shore of the High Rhine just opposite the German town of Gailingen am Hochrhein.

The earliest traces of a settlement are Stone and Bronze Age scattered objects found in the shallow valleys of the district and on the banks of the Rhine.

The reference in a deed of the Abbey of St. Gall from 757 mention an Alamanni village, which was probably on the plateau south of the church.

In 1178 Count Hartmann III of Kyburg, raised the village to town and probably appointed a Ministerialis (unfree knights in the service of a feudal overlord) family as the Stewards of Diessenhofen.

After the extinction of the Kyburgs and the transition of sovereignty to the Habsburgs in 1264, the city developed as one of the cornerstones of the region.

The Stewards, who sat at Unterhof Castle, temporarily united both the Vogt and Schultheiss offices into a single person.

The town was besieged for ten days before it was captured, but, much like Frauenfeld, it retained certain privileges in the new Thurgau.

These included both the high and low courts and the recently acquired customs, tax and Vogt rights, as well as the castle.

During the 16th century, the town gained the low court rights over most of the modern Diessenhofen District.

Diessenhofen's court decisions did not have to be approved by the Governor in Frauenfeld, but went directly to the Confederation Council, in contrast to the rest of Thurgau.

The Mass was abolished in 1529 by the Protestant pastor, who also ordered the confiscation of Catholic Church property.

Diessenhofen supported the city of Zurich in the Second war of Kappel in 1531, which ended in a Protestant defeat.

In 1401 a Jewish man was successfully, but falsely, prosecuted for ritual murder, which led to further persecution in Winterthur and Schaffhausen.

[3] Since the Early Middle Ages the district has been known as the granary of the Thurgau due to its extensive and productive grain fields.

The limited industry and area provided too little money to support the formation of trade-oriented guilds.

The town's location on the Rhine favored the development of fisheries, and it benefited from the salt trade.

[13] The historical population is given in the following table:[3] Unterhof Castle, City Archives in the Rathaus (Town council house), Former Dominican Monastery of St. Katharinental with its granary, the zum Goldenen Löwen House and the Goldener Leuen Collection, the Rheinbrücke (Rhine Bridge), and the city walls with Siegelturm are listed as Swiss heritage site of national significance.

Both the town of Diessenhofen and St Katharinental Monastery are part of the Inventory of Swiss Heritage Sites.

One of the three data centers of SWIFT, the international bank messaging network, is situated in Diessenhofen since 2009.

[17] Diessenhofen sits on the Lake Line between Schaffhausen and Rorschach and has two railway stations: Diessenhofen, at the southern edge of the city center, and St. Katharinental, near the former Dominican monastery, west of the city center.

At the lower primary level, there are 93 children or 46.5% of the total population who are female, 52 or 26.0% are not Swiss citizens and 48 or 24.0% do not speak German natively.

In the upper primary level, there are 100 or 42.4% who are female, 59 or 25.0% are not Swiss citizens and 63 or 26.7% do not speak German natively.

There are 220 teenagers who are in the advanced school, of which 125 or 56.8% are female, 45 or 20.5% are not Swiss citizens and 41 or 18.6% do not speak German natively.

There are 19 teenagers who are in the standard school, of which 8 or 42.1% are female, 5 or 26.3% are not Swiss citizens and 5 or 26.3% do not speak German natively.

Finally, there are 16 teenagers who are in special or remedial classes, of which 6 or 37.5% are female, 8 or 50.0% are not Swiss citizens and 8 or 50.0% do not speak German natively.