Christmas Island is a site of international conservation significance and home to many endemic and threatened species. In this work we used spatial prioritisation tools to build an understanding of how biodiversity values on Christmas Island are distributed. The aims of this were to evaluate the current protection of priority species and habitats within the National Park, to identify key areas of priority within the National Park, and to identify important areas for biodiversity that are not currently protected. The spatial prioritisation tool hierarchically ranks each 100 square-metre location on Christmas Island based on its biodiversity value, using information on the mapped distributions of priority species and habitats. The top ranked sites together represent the core habitats of all included species. The highly ranked sites are also those most irreplaceable, as there are few or no locations with same biodiversity values. It is important to note that the spatial prioritisation process ranks all areas within a set study area (i.e. Christmas Island). It does not represent an absolute rating of the conservation value of any individual location but a relative value between locations within the study area. That is, areas in the top and bottom 10% ranked priorities each represent exactly 10% of the study area, and so their rankings need to be considered holistically across the study area. Lower ranked areas may still be of high conservation value for the species and habitats assessed.