Biodiversity and food security are connected in many ways. Across scales from genes to species, landscapes, and biomes, biodiversity is an important resource for humanity. It is the key for a broad range of services provided by ecosystems. Biodiversity helps regulate the nutrient cycle and water (e.g., floods) and mitigates impacts of climate change. Biodiversity is also of direct importance for human well-being and for cultural and other values including recreation. The provisioning of clean water and diverse food supply makes it vital for all people. Biodiversity at all levels, including the diversity of genes, species, and ecosystems, is lost at alarming rates. Critical factors for these trends are habitat destruction, global warming, and the uncontrolled spread of alien species. Pollution, nitrogen deposition, and shifts in precipitation further affect biodiversity. Food security faces significant challenges due to population growth, poverty, globalization, climate change, and other factors. Supplying healthy food to all citizens is crucial for global development—to reach it, not only food production but also equitable access to food for all people must be improved substantially. Biodiversity loss and global food security are hence two major challenges of our time. Linking these two areas from a research perspective and seeking synergies between them are likely to generate multiple benefits for social, ecological, and economic development.