Agriculture generates vast quantities of crop residues, animal manure, and agro-processing waste, much of which is still treated as a disposal burden rather than a productive resource. This contributes to nutrient loss, air pollution, and missed economic opportunities. As sustainability and resilience become increasingly important, the circular economy (CE) offers a framework for transforming agricultural waste into compost, bioenergy, soil amendments, and biobased materials. However, implementation remains complex. This chapter examines how CE principles can be applied to agricultural waste systems and why technically viable approaches often struggle under economic, social, and institutional constraints. Drawing on examples from Africa, Latin America, and Asia, it highlights the importance of local knowledge, existing value chains, infrastructure, finance, and governance. It also explores key challenges, including subsidy dependence, additional labour demands on rural households, and the tendency of advanced technologies to benefit larger, better-resourced actors over smallholders. Emerging opportunities such as decentralized biorefineries, improved quality standards, digital advisory tools, and targeted climate finance are also considered. The chapter argues that successful circular agricultural systems require context-specific approaches that balance technological feasibility with social, economic, and institutional realities.