The escalating global population necessitates a paradigm shift in agricultural practices to ensure food security while minimizing environmental impact. Traditional farming methods often rely on excessive chemical inputs, leading to soil degradation, water pollution, and greenhouse gas emissions. Agro-nanotechnology, a burgeoning field, offers innovative solutions to these challenges by leveraging nanomaterials to enhance crop productivity and resource efficiency. Among these, copper oxide nanoparticles (CuO NPs) have garnered significant attention due to their multifaceted applications as nano-fertilizers, nano-pesticides, and soil amendments. This comprehensive review explores the recent advances and diverse applications of CuO NPs in sustainable farming. We delve into various synthesis methods, emphasizing green chemistry approaches, and critically examine their mechanisms of action in promoting plant growth, enhancing nutrient uptake, and providing robust protection against a spectrum of plant pathogens and pests. Furthermore, the article addresses the crucial environmental interactions of CuO NPs within soil and aquatic systems, considering factors such as pH, organic matter, and their potential ecotoxicity. While highlighting the immense promise of CuO NPs for revolutionizing agricultural sustainability, this review also discusses the inherent challenges, including concerns regarding long-term environmental fate, bioaccumulation, and regulatory frameworks. By synthesizing current knowledge, this article aims to provide a foundational understanding for researchers and agricultural practitioners, guiding the responsible development and deployment of CuO NPs for a more productive, resilient, and environmentally sound agricultural future.