Antimicrobial resistance (AMR) is accelerating globally, reducing the effectiveness of conventional antibiotics and increasing the burden of persistent infections. Plant-derived antimicrobials such as polyphenols, terpenoids, alkaloids, and essential oils offer broad bioactivity and chemical diversity, but their clinical translation is often limited by poor water solubility, instability, rapid clearance, and variable potency. "Nanoantibiotics" integrate antimicrobial agents with nanoscale carriers or are nanomaterials with intrinsic antimicrobial activity, enabling higher local drug concentration, improved bioavailability, controlled release, and antibiofilm performance. This review summarizes plant-derived nanoantibiotics, focusing on green-synthesized metal/metal-oxide nanoparticles using plant extracts, nanoencapsulated phytochemicals, and phytochemical-functionalized nanocarriers. This review discusses mechanisms of action (membrane disruption, reactive oxygen species generation, enzyme inhibition, and quorum-sensing interference), formulation strategies, antibiofilm and wound-healing applications, and current challenges including standardization, toxicity, and regulatory pathways. Finally, this review outlines future directions such as stimuli-responsive systems, synergistic phytochemical antibiotic co-delivery and scalable green manufacturing.