With looming environmental problems and the global energy crisis, fully green composites of natural fibers and biodegradable resin have increasingly attracted research interest because of their advantages of low cost, renewable resource usage, and biodegradability. Recent studies and developments are reviewed in this article, including short fiber green composites, unidirectional green composites, textile and cross-ply green composites, and technologies for improvement of natural fibers and these composites. Fabrication methods, molding conditions, and mechanical properties of the composites are discussed in detail. A key approach of natural fiber toughness improvement by chemical treatment along with its effect on the composites is reported as an excellent example. Finally, future development trends related to fully green composites are predicted.