The Otago Peninsula is a long, hilly indented finger of land that forms the easternmost part of Dunedin, New Zealand. Volcanic in origin, it forms one wall of the eroded valley that now forms Otago Harbour. The peninsula lies south-east of Otago Harbour and runs parallel to the mainland for 20 km, with a maximum width of 9 km. It is joined to the mainland at the south-west end by a narrow isthmus about 1.5 km wide.

The suburbs of Dunedin encroach onto the western end of the peninsula, and seven townships and communities lie along the harbourside shore. The majority of the land is sparsely populated and occupied by steep open pasture. The peninsula is home to many species of wildlife, notably seabirds, pinnipeds, and penguins, and several ecotourism businesses operate in the area.

The peninsula was formed at the same time as the hills that face it across the harbour, as part of a large, long-extinct, volcano. Several of the peninsula's peaks, notably the aptly named Harbour Cone, clearly show these volcanic origins in their form. These rocks were built up between 13 and 10 million years ago.