Osterøy is an island situated northeast of the city of Bergen in Vestland county, Norway.

With a total area of 328 square kilometres (127 sq mi), it is the largest Norwegian island not located directly adjacent to the ocean, and the second largest such island in Northern Europe[citation needed].

The vast majority of the island's population lives in Osterøy municipality (7,305 inhabitants as of 2008).

The highest mountain on Osterøy is the 868-metre (2,848 ft) tall Høgafjellet.

The other is the Kallestadsundet Bridge which connects the northeastern tip of the island to the mainland.