The Oberaargau lies on the Swiss Plateau between the large population centers of Bern and Zürich and has therefore become a major thoroughfare for traffic running both east and west and north and south.

The Aar River traverses it from west to east, and the primary motorway of Switzerland (the A1) and the main Bern-Zürich railway run through it, making it a central transport region.

Since the building of the motorway, the primary economic development has taken place in the north, at the foot of the Jura Mountains, particularly in the towns of Wiedlisbach and Niederbipp.

[1] It is part of the Emmental-Oberaargau administrative region and includes 45 municipalities over an area of (based on the 2004/09/16 survey) of 331.04 km2 (127.82 sq mi), [a] and as of 31 December 2020, 82,472 residents.

In the High Middle Ages, the area was divided among the counts of Froburg, Aarwangen (later Grünenberg), Zähringen (later the Habsburgs).