Cassolnovo is a comune, or municipality, located in the Province of Pavia within the Lombardy region of northern Italy. It is situated approximately 30 km (19 mi) southwest of Milan and about 35 km (22 mi) northwest of Pavia.
As of December 31, 2004, the municipality covered an area of 32.0 km² (12.4 sq mi) and had a recorded population of 6,203 residents.