Diemerswil is a former municipality in the Bern-Mittelland administrative district in the Canton of Bern in Switzerland . On 1 January 2023 the former municipality of Diemerswil merged to form the municipality of Münchenbuchsee.

Diemerswil is first mentioned in 1257 as Diemarswile.

The earliest trace of people in the area is a Hallstatt culture grave mound with a cart or wagon, in the Brandwald. During the Middle Ages it belonged to the Herrschaft, court and parish of the Münchenbuchsee Commandery . After the Commandery was secularized in 1528, the village became part of the Bernese bailiwick of Münchenbuchsee.