The switch to sustainable materials in the twenty-first century has promoted major innovations in polymer composites, especially with the introduction of green composites. These eco-friendly materials consist of the bio-based matrices of polylactic acid (PLA), thermoplastic starch (TPS) and lignin-based polymers and reinforcing with the agriculture wastes of rice husk, wheat straw, coconut shells, and banana fibers. This review is aimed at giving a complete, up to date picture of the latest changes and developments in green composites, including the type of bio-based matrices, functionalization of the agro-waste fillers and of those, and methods of fabrication (such as extrusion, compression molding, and solvent casting). It further examines the mechanic, thermal, morphological, and biodegradation properties of such mixtures and also points out their use in packaging, automobile, construction, biomedical, and electronic industries. Although some areas of scalability and performance homogeneity still exist, there has been a narrowing of the gap between green and conventional composite by the improvement of compatibilization techniques and nanofiller incorporation. The green revolution not only contributes to the environmental sustainability but also a valuable use route of agro-residues as it facilitates the principles of a circular economy and rural economic growth.