The town of Dundas was incorporated in 1847 as part of Wentworth County. It was named by John Graves Simcoe, Lieutenant Governor of Upper Canada, for his friend Henry Dundas, 1st Viscount Melville, a Scottish lawyer and politician who never visited North America.
In the late 18th and early 19th centuries, Dundas enjoyed considerable economic prosperity through its access to Lake Ontario via the Desjardins Canal, and was an important town in Upper Canada and Canada West. It was later surpassed as the economic powerhouse of the area by Hamilton, but for decades it led in importance. A number of Ontario cities (including Toronto) retain streets named Dundas Street, which serve as evidence of its onetime importance. Dundas was once the terminus of Toronto's Dundas Street (also known as Highway 5), one of the earliest routes used by Ontario's first settlers.
With the establishment of McMaster University in nearby west Hamilton in 1930, Dundas gradually became a bedroom community of the university faculty and students, with a thriving arts community. Dundas has a large community of potters and several studio shows/walking tours of the town feature their work each year.
Amalgamation with Hamilton has been proposed on a number of different occasions throughout the history of Dundas, particularly in the 1970s at the time of the formation of the city of Cambridge from a number of smaller towns including Galt, Preston and Hespeler.
Instead, Dundas and Hamilton became two of six second-tier municipalities in the Regional Municipality of Hamilton-Wentworth. There was rough parity between Hamilton and suburban or rural members of the regional council, and it seemed likely that Dundas and other smaller communities like Ancaster had preserved their identity from encroachment by Hamilton.