[4][5] The land was first given to Charles Lemoyne by the governor of New France at the time, the Comte de Frontenac with the intention of setting up a seigneurie in the area.

The seigneurie was bought by Marguerite d'Youville, a founder of the Quebec religious society the Grey Nuns in 1765 and 10 years later construction began on the Church of Saint-Joachim.

With the United States having declared war on Britain in 1812, Châteauguay was seen as little more than a good vantage point to post troops to defend Montreal against an invasion.

In November 1838, members of the rebel group, including some of their leaders, were arrested: François-Maurice Lepailleur, who was later exiled to Australia, and two natives of Châteauguay, Joseph Duquet and Joseph-Narcisse Cardinal, both of whom were later hanged at Au-Pied-du-Courant Prison and subsequently interred beneath a monument to the Patriotes at Notre-Dame-des-Neiges Cemetery in Montreal.

In 1982, with the passage of the Loi sur l'aménagement et l'urbanisme, Québec, the city became part of the Roussillon Regional County Municipality.

As according to the 2021 census, The prominent languages primarily spoken at home by their relative share of the population are French (56%), English (29%) and Spanish (2%).

Châteauguay holds the highest percentage, outside of the Island of Montreal, of Black population in Quebec, which is mostly concentrated in the easternmost part of the city.

Since 1984, Châteauguay has been home to one of the largest HVDC-back-to-back stations in the world with an operating voltage of 140 kV and a maximum transmission rate of 1000 MW.

The Châteauguay public transit system also offers a Taxi-Bus service which allows those people who live outside of the normal bus routes to, by way of transfer, use a taxi funded by CITSO to drop them off at specific points in the city usually within walking distance of their residence.

A small list of Châteauguay schools includes: NOVA Career Centre for adult students recently established itself in a building adjacent to Howard S. Billings.

During the 1980s, three English elementary schools became French due to a demographic shift[citation needed]: The city's local newspaper is Le Soleil (The Sun).