The Columbia Mountains are a group of mountain ranges located in southeastern British Columbia, and partially in Montana, Idaho and Washington. The mountain range covers 135,952 km² (52,491 sq mi). The range is bounded by the Rocky Mountain Trench on the east, and the Kootenay River on the south; their western boundary is the edge of the Interior Plateau. Seventy-five percent of the range is located in Canada and the remaining twenty-five percent in the United States; American geographic classifications place the Columbia Mountains as part of the Rocky Mountains complex but this designation does not apply in Canada (despite a British Columbia government tourism campaign to rebrand their southern portion as the "Kootenay Rockies"). Mount Sir Sandford is the highest mountain in the range reaching 3,519 metres (11,545 ft).

The Columbia Mountains are made up of four large ranges:

Additionally lower areas to the west of the main ranges are sometimes included in the description of the Cariboo Mountains: