Oeno Island is located 143 kilometres (89 mi) northwest of Pitcairn Island, at 23°55′26″S 130°44′03″W. Oeno Atoll measures about 5 kilometres (3.1 mi) in diameter, including the central lagoon, with a total area exceeding 20 square kilometres (7.7 sq mi). There are two larger and three smaller islets on or within the rim of the atoll. Their aggregate land area is only 0.69 square kilometres (170 acres).
The main island (Oeno Island), is about 50 hectares (120 acres) in area, has forest and scrub with pandanus and palm trees. It is located in the southwest part of the atoll’s lagoon. There is a water tap installed on the island. The maximum elevation is less than 5 metres (16 ft). Sandy Island (or Islands) is to the northeast, within the lagoon, and may be an ephemeral island. Three smaller islets are to the south and west of the main island.