The colonial militias in Canada were made up of various militias prior to Confederation in 1867. During the period of New France and Acadia, Newfoundland Colony, and Nova Scotia (1605–1763), these militias were made up of Canadiens (French Canadians), First Nations, British and Acadians. Traditionally, the Canadian Militia was the name used for the local sedentary militia regiments throughout the Canadas.

However, the term "militia" was also used to refer to the Canadian regular professional land forces, beginning with the passing of the Militia Act of 1855. Passed by the Legislative Assembly of the Province of Canada, the act created the Active Militia, later referred to as the Permanent Active Militia. After PAM's formation, the remaining sedentary colonial militia regiments were collectively referred to as the Non-Permanent Active Militia (NPAM). The terms PAM and NPAM continued to be used in Canada until 1940, when the Canadian militias was reorganized into the Canadian Army. The term Militia is still used to refer to the Canadian Army's part-time Primary Reserve.

Military service has been part of Canadian life since the 17th century in New France, where colonists were required to serve in local militia to support regular units of the French army and navy. In 1651, Pierre Boucher received a commission of captain from the governor of New France and asked to raise militia corps in Trois-Rivières. Until the arrival of the Carignan-Salières Regiment in 1665, militia corps were the only defence of New France. In the long struggle between the French and British colonies, they were organized into companies, usually one per church parish, and structured in the same way as a regular French infantry company. The Governor General, Louis de Buade de Frontenac, arranged during the 1690s to provide all militiamen with clothing and equipment. This consisted generally of a capote, a breechcloth, leggings, a blanket, moccasins, a knife and two shirts, The clothing did not constitute a military uniform but was simply Canadian-style civilian wear. Since these men were not paid, this was a relatively economical way of maintaining an effective militia. British and colonial American troops found that the Indigenous-style tactics (i.e., guerrilla warfare, scalping) of the Canadian militia made them a formidable adversary. Perhaps the two most famous Canadian attacks against New England were the Siege of Pemaquid (1696) and the Raid on Deerfield (1704).

The success of the Canadians was underscored during the French and Indian War by George Washington's defeat at Great Meadows and Edward Braddock's embarrassment at the Monongahela River. The British response was to create new "ranger" and "light infantry" units adept at woodland warfare. When France ceded Canada to Great Britain in 1763, defence of the territory remained a duty shared by Canadian and British colonists, Indian nations, and the regular forces of Britain. As the colonies advanced to nationhood, its people were called to their own defence three times in the next 100 years.

Approximate numbers of militiamen in New France in 1759:

Until the establishment of Halifax (1749), the militia units in Acadia (present day Nova Scotia and New Brunswick) were primarily Mi'kmaq, Maliseet and Acadian militia. Before the British Conquest of Acadia in 1710, these militias fought the New Englanders in King William's War and Queen Anne's War. After the conquest, the Mi'kmaq, Acadian and Maliseet militias continued to fight the British through Father Rale's War, King George's War, and Father Le Loutre's War. The two latter wars saw the arrival Gorham's Rangers, the first British militias established in the colony (the British regulars of the 40th Regiment of Foot was raised in the colony 1720). The Mi'kmaq and Acadian militias continued to fight in Nova Scotia throughout the French and Indian War.

In 1775, during the American Revolutionary War, plans to invade Canada were drawn up as the first major military initiative by the newly formed Continental Army. The objective of the campaign was to gain military control of the British Province of Quebec (modern day Canada), and convince the French-speaking Canadiens to join the revolution on the side of the Thirteen Colonies. There were only two British regiments in the colony of Quebec. Companies of Canadian volunteers had to be raised to support the regular troops. Pro-American sympathies were a problem among the anglophone company raised by the Montreal merchants. In November 1775, Governor Carleton organized the defenders of Quebec City to face a siege by the American rebels. British regular troops were few in number. Canadian militia, from both the anglophone and francophone communities, made up the majority of the defenders. The militia of Quebec City was divided into two sections in 1775—'Canadian Militia' drawn from the francophone population, and 'British Militia' made up of anglophones. During the siege of Quebec, both were issued with the same uniform: green coat without lapels, with green facings; buff waistcoats and breeches; tricorne hat. The uniforms were drawn from stocks sent from Britain in the summer of 1775 for a proposed but never raised corps of Canadian light infantry.

In the aftermath of the American Revolutionary came an exodus of 40,000 Loyalists into the Canadas, Nova Scotia, and New Brunswick, joined by many of the Six Nations Iroquois who had remained loyal to the United Kingdom. Since many of the new Canadians were also veterans of Loyalist regiments, they brought both the British sympathies and the military training to establish competent professional forces to oppose the perceived American threat. Called "fencibles", the new units were organized within the British army, but charged wholly with the defence of their home colonies. Their professional presence also enhanced training for the citizen militia and established many traditions that continue to modern times.