Chemainus is a community in the Chemainus Valley on the east coast of southern Vancouver Island, British Columbia, Canada.

Founded as an unincorporated logging town in 1858, Chemainus is now famous for its 39 outdoor murals. This outdoor gallery has given birth to many businesses, including a theatre, antiques dealers, and eateries. The tourist industry stemming from the murals helped rejuvenate the town after its large sawmill closed in the early 1980s and was replaced by a smaller, more efficient, mill.

The name Chemainus comes from the native shaman and prophet "Tsa-meeun-is" meaning broken chest. Legend says that the man survived a massive wound in his chest to become a powerful chief. His people took his name to identify their community, the Stz'uminus First Nation.

A BC Ferry terminal is located in Chemainus, which provides service to Thetis Island and Penelakut Island (previously Kuper).

In January 2006, a Boeing 737 aircraft was sunk off the coast in order to build an artificial reef, attracting divers from around the world.