Copper nanoparticles (CuNPs) have attracted considerable scientific interest due to their cost-effectiveness, multifunctional properties, and wide-ranging applications in biomedical, environmental, and electronic fields. Conventional synthesis routes, however, commonly rely on hazardous reagents, energy-intensive processes, and generate environmentally harmful by-products. In response, plant-mediated green synthesis has emerged as a sustainable alternative. This review critically examines studies reported between 2011 and 2025, emphasizing the role of plant phytochemicals as natural reducing and capping agents in CuNP formation. Key synthesis parameters, characterization techniques, and application prospects are systematically discussed. Despite significant advancements—particularly in recent years—challenges related to reproducibility, oxidation stability, and large-scale implementation remain unresolved. The review concludes that the development of standardized protocols and scalable green methodologies is essential to advance plant-based CuNP synthesis toward industrial and commercial viability.

Keywords: Copper Nanoparticle; Phyto-Fabrication; Sustainable Nanotechnology