Patersonia neocaledonica sp. nov., a new endemic species from New Caledonia of this predominantly Australian genus, is the first record of Iridaceae as native from this southwestern Pacific island. Eighteen species of Patersonia occur in Australia, and one or several more (depending on taxonomy) occur in Malesia, including New Guinea, where they grow in temperate highland areas. Patersonia neocaledonica sp. nov. is distinguished by the fan of relatively broad, sword-shaped to subfalcate leaves with woolly margins, large, brown inflorescence spathes 35 mm long, particularly large white flowers and woolly tomenrose ovary, bract margins and septa of the capsules. Known from a single population subjected to fire and impacts from human visitors, P. neocaledonica sp. nov. is assigned a preliminary threat assessment of Critically Endangered.