The municipality sits on the island of Osterøy, and it is surrounded by several fjords: Osterfjorden-Romarheimsfjorden, Sørfjorden, and Veafjorden.
Osterøy contains four "urban settlements", as defined by Statistics Norway and as of 1 January 2012: Valestrandfossen (1,101 inhabitants), Lonevåg (572 inhabitants), Hausvik (561 inhabitants), and Fotlandsvåg (254 inhabitants) [REF].