Castellazzo Bormida ( Piedmontese ël Cast passage at Bormia ) is a municipality with 4611 (as of 31 December 2012) a population of Alessandria in the Italian province (AL ), Region Piedmont.
The municipality consists of the villages Fontanasse. The neighboring municipalities are Alessandria, Borgoratto Alessandrino, Casal Cermelli, Castelspina, Frascaro, Frugarolo, Gamalero, Oviglio and Predosa. The patron saint of the town is Santo Stefano, Our Lady of Sorrows, San Paolo della Croce.
The village lies at an altitude of 104 m above sea level. The municipality covers an area of 45.19 km ².