Großgmain lies in the Salzburg Flachgau region in the northern foothills of the Untersberg massif, directly on the border with Bayerisch Gmain in the German state of Bavaria.

The Gmain area, first mentioned in a 712 deed of donation issued by Duke Theodbert of Bavaria, is an old settlement ground, a fertile plain stretching along the northern rim of the Berchtesgaden Alps.

When the Archbishops of Salzburg achieved the status of Prince-bishops, the Weißbach became the western border of the immediate estates in the region.

Though the villages of Großgmain und Bayerisch Gmain were part of different dominions, the sense of a common bond among the local population was preserved up to today.

In 1938, it was annexed by Germany, and in April 1941, the Oflag 78 prisoner-of-war camp was established in the town, however it was relocated to Hohenfels, Bavaria.