Oberdiessbach is a municipality in the Bern-Mittelland administrative district in the Canton of Bern in Switzerland. On 1 January 2010 the former municipality of Aeschlen and on 1 January 2014, Bleiken bei Oberdiessbach merged into the municipality of Oberdiessbach.

Oberdiessbach is first mentioned in 1218 as Tiecebac. Until 1870 it was known as Diessbach.

Oberdiessbach, at that time known as Diessbach, was the center of the late medieval Herrschaft of Diessbach. In 1218 it first appears in a record when Hartmann IV of Kyburg inherited the court of Diessbach from the Zähringens.