Bjarkøy is a municipality in Troms county, Norway. The administrative centre of the municipality is the village of Bjarkøy. The municipality is spread across several smaller islands, the biggest being the northern side of Grytøya (the southern part belongs to Harstad). The island of Bjarkøya has the biggest hamlet, also housing the municipal seat.
The parish of Sand was established as a municipality on 1 January 1838 (see formannskapsdistrikt). The southernmost part of the island of Senja (the Senjehesten peninsula) and the Lemmingsvær island (total population of the two locations: 480) was transferred from Bjarkøy to the municipality of Tranøy on 1 January 1964. The municipal boundaries have not changed since.
The municipality is named after the island of Bjarkøya (Old Norse: Bjarkarey). The first element is the genitive case of björk which means "birch" and the last element is øy which means "island". (The name of the island, since it is an old trading place, is maybe inspired by the name of the old and well-known town of Birka in Sweden, which has the same meaning).