Multidrug resistance (MDR) has emerged as a critical challenge in global healthcare and severely compromises the efficacy of conventional antimicrobial and chemotherapeutic strategies. Nano-therapeutics, which leverage the unique physicochemical properties of nano-biomaterials, offer a promising solution to counter MDR by enhancing drug delivery, reducing toxicity, and improving therapeutic outcomes. This chapter explored the potential of nano-biomaterials, including metallic nanoparticles, lipid-based carriers, polymeric nanoparticles, and carbon-based nanostructures, as effective vehicles for combating MDR in bacterial, fungal, viral, and cancer cells. We discuss the mechanisms of MDR, including efflux pumps, biofilm formation, and target modifications, and demonstrate how nano-therapeutics can overcome these barriers. Particular attention has been given to the synergistic effects of nanoformulations with existing antibiotics, targeted drug delivery systems, and sustained release mechanisms. Case studies and clinical applications highlight recent advances and emerging technologies in nano-therapeutics, demonstrating their ability to disrupt biofilm integrity and restore the efficacy of conventional drugs. This chapter addresses critical challenges, including biocompatibility, scalability, and regulatory hurdles, and proposes future directions for research and development. By integrating cutting-edge innovations with practical applications, nano-therapeutics can redefine the treatment landscape for MDR, thereby offering new hope for global health.