Walpole Island is an island and First Nation reserve in southwestern Ontario, Canada, on the border between Ontario and Michigan in the United States. It is located in the mouth of the Saint Clair River on Lake Saint Clair, about 121 kilometres (75 mi) by road from Windsor, Ontario, and 124 kilometres (77 mi) from Detroit, Michigan.

Walpole Island is given (but disputed) as the resting place of Tecumseh, a 19th-century leader of the Shawnee of much renown for his resistance against American westward expansion by forming Tecumseh's confederacy and starting Tecumseh's War.

Walpole Island is unceded territory and is inhabited by the Ojibwe, Potawatomi, and Odawa peoples of the Walpole Island First Nation, who call it Bkejwanong, meaning "where the waters divide" in Anishinaabemowin. In addition to Walpole Island, the reserve includes Squirrel Island, Saint Anne Island (surrounded by Syme and Johnson Rivers), Seaway Island (except a small US portion), Bassett Island, and Potawatomi Island. The river or creeks that separate these islands provide the area with its other commonly used name, Swejwanong or "many forks of a river."

It is independent of, but within the geographic region of, Lambton County and adjoins the municipality of Chatham-Kent and the township of Saint Clair. Across the Saint Clair River to the west are the United States towns of Algonac, Michigan, and Clay Township. Harsen's Island, also unceded Anishinaabe territory, is now on the west side of the international border line. The border was redrawn in the 19th century following disputes between the United Kingdom and the United States; their governments were oblivious to the interests and rights of the Indigenous peoples living on and using these lands. As such, the First Nation is now^[when?] trying to solve their grievances with the Crown with a specific claim.

The name origins of Walpole are uncertain (although possibly related to surveyors Lieutenants Arthur Walpole or John Walpole).

In the late 1600s and early 1700s, what is now known as Walpole Island and the surrounding area was settled by people from the Ojibwe and Odawa nations. In 1844, Jesuits from nearby Sandwich built a mission at the northern point of Walpole Island at the Highbanks. This raised tensions with the Anishinaabeg as the Jesuits were not invited to build on the island and they cut down oak trees that the community did not want to be cut. The relationship between the two groups was further antagonized by the theological debate that Father Pierre Chazelle held with Chief Peterwegeschick and other chief leaders on July 31, 1844. In 1850, the Jesuits left after the mission was razed.

Due to a number of contracts for harvesting oak on the island, drawn up by non-Native resource industries, a large amount of Walpole Island was deforested. The nature of these contracts "created a lasting mistrust between the community, Indian Affairs, and non-Native resource industries".

As part of an effort to colonize the island, Indian Affairs produced an illegal prohibition on the hunting of ducks on Saint Anne's Island. The prohibition was lifted once Aboriginal Title was reaffirmed in 1899.