It drains into Discovery Passage at the northwest end of the Strait of Georgia at the City of Campbell River.

The river was named for Dr. Samuel Campbell, ship's surgeon aboard HMS Plumper from 1857 to 1861.

Three hydroelectric dams are located on the Campbell River: the John Hart Dam, finished in 1947, which impounds John Hart Lake; upstream, the Ladore Dam, completed in 1949 on Lower Campbell Lake; and the Strathcona Dam, completed 1958, impounding Upper Campbell Lake furthest upstream.

[1] Each dam has an accompanying generating station, of which the John Hart Generating Station near the John Hart Dam is the largest.

Combined, the three generating stations account for about 11 percent of Vancouver Island's total electricity supply.