Numerous excavations within the city of Gunzenhausen document that the area was occupied and there was a settlement in pre-historic time. In the year 90 the Romans expelled the Celts, occupied the inhabited areas north of the Donau River and expanded into the Gunzenhausen area. In the year 241 the Alemanni invaded the area and destroyed the fortress. A document from the year 823 supplies the first reliable written reference to Gunzenhausen.
Emperor Ludwig der Fromme conveyed the monastery "Gunzinhusir" to the High-monastery of Ellwangen. Later the "Truhendinger" and the "Oettinger" families became Lords of Gunzenhausen, and in 1368 Gunzenhausen came to the House of Hohenzollern. So the city received the right of holding fairs and was allowed to build city walls, towers and moat, as well as a large church. Gunzenhausen had a big Jewish community and a wonderful mauric synagogue.
In the 1970s eighteen municipalities were combined resulting in the city growing to about 17,000 inhabitants.