The UNESCO World Heritage Convention is unique among international agreements as it deals with both natural and cultural heritage. By conferring one of the highest levels of protection recognized by 195 countries, it ensures a truly global commitment to safeguarding exceptional places. UNESCO natural World Heritage sites are critical for the conservation of ecosystem integrity and biodiversity. While they make up less than 1% of the Earth’s surface, they harbor more than 1/5 of mapped global species richness. This includes over 75,000 species of plants, and over 30,000 species of mammals, birds, fishes, reptiles and amphibians. Cultural World Heritage sites in particular can be an important ally in biodiversity conservation since around 20% of them are located in Key Biodiversity Areas (KBAs). UNESCO World Heritage sites also represent a safe haven for some of the most threatened species on Earth. They are estimated to protect over 20,000 globally threatened species, and are home to some of the last individuals of many iconic species. Today, up to 1/3 of remaining elephants, tigers and pandas can be found in these sites, as well as at least 1 in 10 great apes, girffaes, lions and rhinos. However, even these highly protected sites are today threatened by global climate change and human pressures, including agricultural expansion, infrastructure development, poaching, overexploitation of resources and the proliferation of invasive species. Every 1°C increase in temperature could double the number of species exposed to dangerous climate conditions. Ensuring effective and sustained protection of UNESCO World Heritage sites and surrounding landscapes is crucial for maximizing their value as a solution to tackle the current biodiversity and climate crisis. One way of achieving this is by supporting countries to integrate World Heritage into their National Biodiversity Strategies and Action Plans (NBSAPs), as they are key to implementing the Kunming-Montreal Global Biodiversity Framework (GBF).