The Reform movement in Upper Canada was a political movement in British North America in the mid-19th century.

It started as a rudimentary grouping of loose coalitions that formed around contentious issues. Support was gained in Parliament through petitions meant to sway MPs. However, organized Reform activity emerged in the 1830s when Reformers, like Robert Randal, Jesse Ketchum, Peter Perry, Marshall Spring Bidwell, and William Warren Baldwin, began to emulate the organizational forms of the British Reform Movement and organized Political Unions under the leadership of William Lyon Mackenzie. The British Political Unions had successfully petitioned for the Great Reform Act 1832 that eliminated much political corruption in the British parliamentary system. Those who adopted these new forms of public mobilization for democratic reform in Upper Canada were inspired by the more radical Owenite Socialists who led the British Chartist and Mechanics Institute movements.

Organized collective reform activity began with Robert Fleming Gourlay (pronounced "gore-lay"). Gourlay was a well-connected Scottish emigrant who arrived in 1817, hoping to encourage "assisted emigration" of the poor from Britain. He solicited information on the colony through township questionnaires, and soon became a critic of government mismanagement. When the local legislature ignored his call for an inquiry, he called for a petition to the British Parliament. He organized township meetings, and a provincial convention - which the government considered dangerous and seditious. Gourlay was tried in December 1818 under the 1804 Sedition Act and jailed for 8 months. He was banished from the province in August 1819. His expulsion made him a martyr in the reform community.

A loose committee of the "Friends of Religious Liberty" composed of William Lyon Mackenzie, Jesse Ketchum, Egerton Ryerson, Joseph Shepard and nineteen others, chaired by William Warren Baldwin (who was one of only 3 Anglicans) circulated a petition against an "Established Church" in the province. It gained 10,000 signatures by the time it was sent to the British Parliament in March 1831. The petition gained little due to direct intervention by the Church of England.

By mid-1831, the leaders of the reform faction in the House of Assembly such as Rolph and the Baldwins were discouraged and withdrew from politics. At this point, William Lyon Mackenzie organized a "General Committee on the State of the Province" which organized the first truly provincial petitioning campaign to protest a whole series of ills. Although 10,000 signatures were obtained the only real gain was to organize the reformers in the province.

Mackenzie's organizational efforts made him many enemies in the House of Assembly. When the House reconvened, Mackenzie was unjustly expelled. Over the next two years, Mackenzie was re-elected only to be expelled a total of five times. As demonstrations in support of Mackenzie were increasingly met with violence by Orangemen, he travelled to England to personally present his appeal in March 1832. Mackenzie's trip to England was to prove inspirational, as he was exposed to the power of the British form of reform activity, the Political Unions, in the run-up to the passage of the Reform Act 1832.

Upper Canadians saw themselves as citizens of Great Britain with all the rights granted by the British Constitution. It is no surprise then, that the Upper Canadian Reform Movement should adopt the organizational forms of the British Reform Movement.

During the late 1820s, large scale, national petitioning campaigns were organized through a new form of organization, the "Political Union". One of the first and largest was the Birmingham Political Union founded in 1830. Its stated aim was to campaign for electoral reform of the House of Commons, "to be achieved by a general political union of the lower and middle classes of the people". Other more radical Political Unions, like the "Metropolitan Political Union" had their roots in Owenite socialism.