New Caledonia is a tropical archipelago with very high biodiversity conservation challenges. Its flora is still imperfectly known while its ecosystems are increasingly degraded by various threats, including mining activity. In this context, there is an urgent need to describe the most threatened species so they can be accounted for in situ conservation programs. In this article, three species new to science are described and illustrated: Croton barrabeae Bruy (Euphorbiaceae), Geijera tartarea T.G.Hartley ex Munzinger & Bruy (Rutaceae) and Tristaniopsis planidisca Lannuzel (Myrtaceae). According to IUCN criteria, each of these species is highly threatened by mining activity.