Biodiversity loss is accelerating around the world. The global rate of species extinction today is orders of magnitude higher than the average rate over the past 10 million years. The global food system is the primary driver of this trend. Over the past 50 years, the conversion of natural ecosystems for crop production or pasture has been the principal cause of habitat loss, in turn reducing biodiversity. Our food system has been shaped over past decades by the ‘cheaper food’ paradigm. Policies and economic structures have aimed to produce ever more food at ever lower cost. Intensified agricultural production degrades soils and ecosystems, driving down the productive capacity of land and necessitating even more intensive food production to keep pace with demand. Growing global consumption of cheaper calories and resource-intensive foods aggravates these pressures. Current food production depends heavily on the use of inputs such as fertilizer, pesticides, energy, land and water, and on unsustainable practices such as monocropping and heavy tilling. This has reduced the variety of landscapes and habitats, threatening or destroying the breeding, feeding and/or nesting of birds, mammals, insects and microbial organisms, and crowding out many native plant species. As a major contributor to global greenhouse gas emissions, our food system is also driving climate change, which further degrades habitats and causes species to disperse to new locations. In turn, this brings new species into contact and competition with each other, and creates new opportunities for the emergence of infectious disease. Without reform of our food system, biodiversity loss will continue to accelerate. Further destruction of ecosystems and habitats will threaten our ability to sustain human populations. Reform will rely on the use of three principal levers:Firstly, global dietary patterns need to converge around diets based more on plants, owing to the disproportionate impact of animal farming on biodiversity, land use and the environment. Such a shift would also benefit the dietary health of populations around the world, and help reduce the risk of pandemics. Global food waste must be reduced significantly. Together, these measures would reduce pressure on resources including land, through reducing demand.Secondly, more land needs to be protected and set aside for nature. The protection of land from conversion or exploitation is the most effective way of preserving biodiversity, so we need to avoid converting land for agriculture. Restoring native ecosystems on spared agricultural land offers the opportunity to increase biodiversity.Thirdly, we need to farm in a more nature-friendly, biodiversity-supporting way, limiting the use of inputs and replacing monoculture with polyculture farming practices. These three levers are in part interdependent. Most notably, the protection and setting aside of land for nature and the shift to nature-friendly farming both depend on dietary change, and will become increasingly difficult to achieve if continued growth in food demand exerts ever-growing pressure on land resources. The year ahead offers a potentially unique window of opportunity for food system redesign. A series of international summits and conferences will take place in 2021, during which the topic of food systems and biodiversity will be a common thread. Importantly, the UN secretary-general will convene the world’s first UN Food Systems Summit (UNFSS) in recognition of the need for a transformation of the food system to improve nutrition security, public health and environmental sustainability. In 2021, governments around the world are expected to unlock unprecedented levels of investment to support economic recovery from the COVID-19 pandemic. Efforts to set in motion a ‘green recovery’ will bring questions of sustainability, equity and societal resilience to the fore, creating new opportunities for joined-up policymaking that affords equal priority to public and planetary health. In light of these opportunities, this paper recommends action on three fronts if efforts to establish a biodiversity-supporting food system are to be advanced in 2021:International decision-makers need to recognize the interdependence of supply-side and demand-side action. Dietary change and a reduction in food waste are critical to breaking the system lock-ins that have driven the intensification of agriculture and the continued conversion of native ecosystems to crop production and pasture.Stakeholders leading on the design and delivery of the UNFSS must ensure that it embeds a ‘food systems approach’ across other key international processes, including UN climate negotiations. The summit should aim to bring together the interdependent policy threads of environmental sustainability, inclusive prosperity, sustainable growth, and improved public health and well-being.International and national decision-makers need to strengthen the coherence between global agreements and national-level action. National dialogues are needed to translate global commitments into action on the ground. At the same time, national accounting frameworks will be key to building understanding of the value of biodiversity, and to supporting biodiversity protection. Global guidelines in policy areas such as responsible investment, dietary change and nature-based climate change mitigation solutions will be needed to guide national-level action plans that can collectively deliver transformative change to the global food system.