De Horsey Island is an island at the mouth of the Skeena River in the North Coast region of British Columbia, Canada, located immediately south of the southern tip of the Tsimpsean Peninsula and immediately east of Smith Island. Separating it from that island is De Horsey Passage, while to its north separating it from the Tsimpsean Peninsula is Eleanor Passage. Kshaoom Indian Reserve No. 23 is on its northwest tip.
The island was named in 1877 for Rear Admiral Algernon Frederick Rous de Horsey, commander in chief on this station from 1876 to 1879. His flagship was the HMS Shah, 26 guns, under Captain Bedford.
Coordinates: 54°07′09″N 130°08′34″W / 54.11917°N 130.14278°W