The administrative centre of Osterøy is the village of Lonevåg in the central part of the island.

The 19th-century musician and composer Ole Bull had a summer home in Valestrandfossen in Osterøy.

[5][6] The municipality sits on the island of Osterøy, and it is surrounded by several fjords: Osterfjorden-Romarheimsfjorden, Sørfjorden, and Veafjorden.

[4] Other rural settlements in Osterøy include Austbygdi, Bruvik, Gjerstad, and Hosanger.

Another interpretation is that it is derived from the word auka which means "increase" or "surpass", thus it could be referring to the large size of the island.

The official blazon is "Argent, three axes fesswise azure blades to the base, 2-1" (Norwegian: I sølv tre blå økser med blada ned, 2-1).

Broad axes were historically used in the construction of timber houses, which has long traditions in the municipality.

The municipal council (Kommunestyre) of Osterøy is made up of 27 representatives that are elected to four year terms.

The ferry named "Ole Bull" is sailing every half-hour from Breistein and Valestrand from early morning to late in the evening.

That part of the island has the Kallestadsundet Bridge connecting it to the rest of Vaksdal municipality from the east.