At the time of the census in May 2001, the population of the city of Hamilton was 490,268. The entire province of Ontario was 11,410,050 people. In the five years between 1996 and 2001, the population of Hamilton grew by 6.1%, which is an average growth for Canadian cities.

Nearly one-quarter of the metropolitan area population of Hamilton was foreign-born, making Hamilton the Canadian city with the third highest proportion of foreign-born citizens after Toronto (44%) and Vancouver (38%).

Hamilton is overwhelmingly populated by people of a white ethnic background. Ninety percent are of a white ethnic background; the remainder consists of East Indian, Chinese, and Caribbean origins. About 8% of immigrants of the 1990s cited Yugoslavia as their country of birth.