The Trans-Canada Highway (French: Route Transcanadienne; abbreviated as the TCH or T-Can) is a transcontinental federal–provincial highway system that travels through all ten provinces of Canada, from the Pacific Ocean on the west coast to the Atlantic Ocean on the east coast. The main route spans 7,476 km (4,645 mi) across the country, one of the longest routes of its type in the world. The highway system is recognizable by its distinctive white-on-green maple leaf route markers, although there are small variations in the markers in some provinces.

While by definition the Trans-Canada Highway is a highway system and has several parallel routes throughout most of the country, the term "Trans-Canada Highway" often refers to the main route that consists of Highway 1 (British Columbia, Alberta, Saskatchewan, and Manitoba), Highway 17 and 417 (Ontario), Autoroute 40, 20 and 85 (Quebec), Highway 2 (New Brunswick), Highway 104 and 105 (Nova Scotia) and Highway 1 (Newfoundland). This route starts in Victoria and ends in St. John's, passes through nine of the ten provinces and connects most of the country's major cities, including Vancouver, Calgary, Winnipeg, Ottawa, Montreal, Quebec City and Fredericton. While the other routes in the system are also technically part of the Trans Canada Highway, they are usually considered either secondary routes or considered to be different highways all together. For example, Highway 16 throughout Western Canada is part of the Trans Canada Highway system, but is almost exclusively referred to as the Yellowhead Highway and is often recognized as its own highway under that name. In comparison, Highway 1 in Western Canada is always referred to as the Trans-Canada Highway, and has a significantly higher traffic volume with a route passing through more major cities than the less important Highway 16 (Yellowhead) TCH route. Therefore Highway 1 is usually considered to be part of the main Trans-Canada Highway route, while Highway 16 is not, although it may be considered a second mainline corridor as it serves a more northerly belt of major cities.

Although the TCH network is strictly a transcontinental system, and does not enter any of Canada's three northern territories or run to the United States border, it does form part of Canada's overall National Highway System (NHS), which does provide connections to the Northwest Territories, Yukon and the border, although the NHS (apart from the TCH sections) is unsigned.