The Cowichan River /ˈkoʊ.ɪtʃən/ is a Canadian Heritage River^[1] on Vancouver Island, in British Columbia, Canada. Its headwater is Cowichan Lake. The river flows east over Skutz Falls and through Marie Canyon towards its mouth at Cowichan Bay. The river's drainage basin is 795 square kilometres (307 sq mi) in size.^[2]

The Cowichan River is the centre of a provincial park, Cowichan River Provincial Park, on southern Vancouver Island. The park is home to hundreds of animal species, including the native and endangered Vancouver Island ermine and more than 200 species of birds.^{[citation needed]}

The river is the namesake of Cowichan Herald Extraordinary at the Canadian Heraldic Authority.^{[citation needed]}

In the decade leading up to 2014, water levels dropped to the point that it "required the trucking of fish up the river," and the Cowichan Valley Regional District instituted water restrictions for residents.^[3]

Water from the river is used in the pulp and paper mill operated by Catalyst Paper in Crofton.^{[citation needed]}

The Cowichan River had once had salmon so plentiful that "old-timers talk about having been able to cross on the backs of fish so thick they were like steppingstones," and was world-renowned for its fly fishing. However, in 2023, due to the impacts of climate change, the river experienced a major fish die-off.^[4]