Altötting was one of the original parts of Bavaria. It was settled by Bavarian tribes shortly after the retreat of the Romans. During the rule of duke Tassilo III (748-788) the place of Ötting was mentioned for the first time (the towns of Altötting and Neuötting are derived from that place). Soon in the 9th century the region became a religious centre with famous churches and monasteries. In the 15th century it became a place of pilgrimage.
The district is located in the alpine upland on the Austrian border. The main axis of the region is the Inn River, which crosses the district from west to east. It is joined by two large tributaries, the Alz River coming from the south and the Salzach, which forms the eastern border of the district. In addition there are several smaller rivers and brooks. The district once was covered with deciduous forests, but is now mainly agriculturally used. However, there are some nature reserves along the lower Alz River and at the mouth of the Salzach River.