Lomello is a comune located in the Province of Pavia within the Lombardy region of northern Italy. It is situated on the right bank of the Agogna river, approximately 50 km southwest of Milan and 30 km west of Pavia.
The municipality gives its name to the surrounding geographical area known as Lomellina. It shares borders with several neighboring municipalities, including Ferrera Erbognone, Galliavola, Mede, Ottobiano, San Giorgio di Lomellina, Semiana, Velezzo Lomellina, and Villa Biscossi.