The increasing need for sustainable agriculture calls for novel solutions to reduce the environmental footprint of traditional fertilizers. In this research, the fabrication and utilization of nano-fertilizers prepared from agro-waste resources are introduced as a double benefit of waste valorization and better nutrient delivery. Through green synthesis routes, agro-waste-derived nanomaterials (such as carbon dots and cellulose nanocrystals) are designed to encapsulate major macro- and micronutrients to provide controlled release and better bioavailability. Experimental data show a 20–35% improvement in nutrient-use efficiency over conventional fertilizers, with less leaching and soil toxicity. Field tests on major crops yield a 15–25% increase in yield, highlighting their capacity to strengthen food security. In addition, lifecycle assessment shows a 30% saving in carbon footprint, in keeping with circular economy principles. This study highlights agro-waste-based nano-fertilizers as a scalable, environmentally friendly innovation, solving problems of resource depletion, waste treatment, and green intensification of agriculture. It is recommended that policymakers and actors prioritize such a development to realize UN Sustainable Development Goals (SDGs) 2 (Zero Hunger) and 12 (Responsible Consumption and Production).