At the top of the flag is a rendition of the Royal Union Flag, defaced in the centre by a crown, and with a setting sun, a view from parliament across the water at the province capital, representing the location of the province of British Columbia at the western end of Canada.

The flag of British Columbia is based upon the 1906 arms of the province, designed by Arthur John Beanlands, the canon of Christ Church Cathedral in Victoria.

Based upon Beanlands' revised design, the flag of British Columbia was introduced on June 14, 1960, by Premier W. A. C. Bennett, and was first flown on board the BC Ferries motor vessel Sidney (later Queen of Sidney).

The setting sun represents the fact that British Columbia is Canada's westernmost province.

It also bears similarities to the arms of Suffolk County Council, the local authority of the county of Suffolk in the United Kingdom, as well as the flag of Kiribati, which features the blue waves for the Pacific Ocean and a sun for its own reasons.