Kapiti Island, sometimes written as Kāpiti Island, is an island nature reserve located 5.6 km (3 mi) off the west coast of the lower North Island of New Zealand and within the Kāpiti Coast District. Parts of the island were previously farmed, but it is now a predator-free sanctuary for endemic birds, including many endangered birds. The island is 10 km (6.2 mi) long, running southwest/northeast, and roughly 2 km (1.2 mi) wide, being more or less rectangular in shape, and has an area of 19.65 km2 (7.59 sq mi).

The Kāpiti Coast District, is a local government district of the Wellington Region in the lower North Island of New Zealand, 50 km north of Wellington City. The district is named after Kapiti Island, a prominent island 5 kilometres (3.1 mi) offshore.