The United Nations Sustainable Development Agenda 2030 calls for a transformative action to eradicate hunger and poverty and is particularly important for food production in developing countries (see SDG 1 Zero Hunger). Farmers in developing countries apply less potassium fertiliser than those in developed countries due to the high cost of imports and unavailability of domestic supplies. A circular economy approach can improve the efficient use of potassium resources throughout their life cycle from “mine to mouth” by identifying problem areas and assisting in designing supply strategies that help address the needs of farmers. As a nutrient, potassium conventionally follows a linear life cycle from mining. Using secondary data sources and literature, we analyse global demand and supply of potassium to quantify and illustrate the major supply shortages in the Global South. This study identifies six options to improve potassium availability: (1) expanding conventional potassium mining and distribution systems serves those who can afford globally-traded fertiliser products; (2) seeking alternative sources of potassium, such as remineralisers, that provide a local source that is accessible to poorer farmers, and in many cases helps the circular economy of local mining operations that focus on other products; (3) improving markets by supporting trade and mitigating some of the disadvantages encountered in developing countries, such as transport and small scale of purchasing; (4) increasing the use of organic fertilisers, such as sewage and manures; (5) reusing crop residues and other farm wastes as sources of potassium, regarding a farm unit as a closed system as far as is practicable; and (6) recycling food waste so that nutrients return to the land, rather than to discard. Existing restrictions and practices mean that there is no single solution to enhance food production in the Global South using the circular economy principles. However, if these circular economy principles and policies are considered at farm to country scale progress can be made.