After much lobbying by environmental groups, the BC Government is adding 380,000 additional hectares of protected land.
The chunk of land is twice the size of Jamaica.
A cull of the mountain caribou's natural predators in the region is also planned, officials said.
The decision by the British Columbia government follows three years of lobbying by 10 environmental groups concerned about the animals' fate.
British Columbia Agriculture and Lands Minister Pat Bell told AFP he received 15,000 emails from citizens pleading with him to save the endangered species.
Mountain caribou, represented on the Canadian quarter coin since 1937, are cousins of the woodland caribou found mostly in northern Canada and parts of Alaska.
Only a dozen mountain caribou herds live in steep mountain ranges in southeast British Columbia and parts of the US states of Washington, Idaho and Montana, using their huge hooves to cross deep snow at higher elevations to escape wolves and cougars in winter.
Photo by Alka3en