The Sesia (Latin Sesites or Sessites) is a river in Piedmont, north-western Italy, tributary to the Po.

Its sources are the glaciers of Monte Rosa at the border with Switzerland.

It flows through the Alpine valley Valsesia and the towns Varallo Sesia, Quarona, Borgosesia and Vercelli.

The Sesia flows into the Po River near Casale Monferrato.

This article related to a river in Italy is a stub.