Breast cancer continues to be a major cause of death among women globally, with triple-negative breast cancer (TNBC) presenting a particularly difficult challenge due to its aggressive behaviour and the lack of effective treatment options. Nanotechnology, particularly the use of silver nanoparticles (AgNPs), has emerged as a promising avenue in oncological research. This review explores into the escalating field of green synthesis of nanoparticles, emphasizing sustainable approaches utilizing plant-based resources. Critical factors influencing nanoparticle synthesis, including reaction conditions, precursor types, and plant phytochemicals, are explored alongside advanced characterization techniques essential for evaluating nanoparticle properties. Special focus is given to the phytofabrication of silver nanoparticles and their multifaceted roles in breast cancer treatment, with detailed insights into their mechanisms, such as inducing apoptosis, generating reactive oxygen species (ROS), and disrupting mitochondrial function, particularly in TNBC cells. The review further highlights the advantages of plant-derived AgNPs, such as biocompatibility and reduced toxicity, while addressing challenges like scalability, reproducibility, and regulatory hurdles. Concluding with future prospects, this paper reflects the potential of green-synthesized AgNPs as a keystone in next-generation cancer therapeutics, paving the way for innovative and eco-friendly approaches in oncology.