It is not widely recognised that the reuse of phosphorus will be crucial to achieving future food security, supporting farmer livelihoods and buffering against emerging geopolitical risks. All farmers need access to phosphorus fertilisers to grow crops, yet just five countries control 85% of the world’s main source: phosphate rock. Morocco alone controls three-quarters of the world’s remaining phosphate. These phosphate reserves are non-renewable, and becoming increasingly scarce and expensive. Already one in six farmers cannot access fertiliser markets. The 800% phosphate price spike in 2008 demonstrated the vulnerability of global and local food systems to even a short-term disruption in supply. At the same time, a staggering 80% of phosphorus is lost or wasted in the supply chain between mine, farm and fork. Much of this ends up in rivers and lakes, leading to widespread nutrient pollution and algal blooms. The good news is that phosphorus can be recovered and reused from all organic sources in the food system: food waste, human excreta, manure, crop waste. Indeed, there are over 50 low- to high-tech solutions. However, phosphorus vulnerability is very context-specific, and what works in one country may be inappropriate or ineffective in another region. This case study highlights a path forward, including examples from Vietnam, Malawi and Australia. Investing in phosphorus reuse creates locally available ‘renewable fertilisers’. This simultaneously: reduces dependence on imports from geopolitically risky regions and therefore buffers against future price spikes and supply disruptions; reduces phosphorus waste in the food supply chain; and reduces the risk of nutrient pollution.