The northeastern part of Imathia, along the lower course of the river Aliakmonas, is a vast agricultural plain known as Kampania or Roumlouki.

The Pierian Mountains reach into the southern part of Imathia, south of the Aliakmonas.

The regional unit borders on Pieria to the south, Kozani to the west, Pella to the north and Thessaloniki to the east.

Imathia has a mainly Mediterranean climate with warm, dry summers and mild, wet winters.

Imathia was named after the historic region Emathia, which was used by several classical authors as a synonym for Bottiaea or even all of Macedon.