Montmagny is a city in the Montmagny Regional County Municipality within the Chaudière-Appalaches region of Quebec, Canada. It is the county seat and had a population, as of the Canada 2021 Census, of 10,999. The city is on the south shore of the Saint Lawrence River, east of Quebec City, and was founded more than 350 years ago. It is Canada's Snow Goose Capital, and festivals include the International Accordion Festival in September and the Festival of the Snow Geese in October.