Prehistoric Orkney refers only to the prehistory of the Orkney archipelago of Scotland that begins with human occupation. Although some records referring to Orkney survive that were written during the Roman invasions of Scotland, “prehistory” in northern Scotland is defined as lasting until the start of Scotland's Early Historic Period.

A chambered cairn is a burial monument, usually constructed during the Neolithic, consisting of a sizeable chamber around and over which a cairn of stones was constructed. Some chambered cairns are also passage-graves. They are found throughout Britain and Ireland, with the largest number in Scotland.