Water scarcity demands sustainable desalination technologies. Solar-driven methods, particularly Thermohaline Solar Membrane Distillation (TSMD), offer energy-efficient and eco-friendly solutions. TSMD leverages natural thermohaline convection, driven by temperature and salinity gradients, to enhance water production while preventing salt accumulation—a persistent challenge in traditional methods. By combining confined saline layers, hydrophobic membranes, and advanced solar absorbers, TSMD achieves continuous operation even under high salinity (up to 20% brine). Compared to conventional techniques like Multi-Stage Flash (MSF), Multi-Effect Distillation (MED), and Reverse Osmosis (RO), TSMD demonstrates superior energy efficiency, environmental sustainability, and long-term stability. Innovations such as interfacial solar absorbers and modular multistage designs enable water production rates of up to 4.74 kg/m²/hr with competitive solar-to-water efficiencies. Additionally, TSMD minimizes brine discharge and carbon emissions, addressing critical environmental concerns. While scaling TSMD for diverse climates remains a challenge, advancements in material engineering and hybrid systems show promise. Integration with nanophotonics and thermal energy storage could further improve performance in off-grid and variable sunlight conditions. This review highlights TSMD’s potential as a cost-effective, durable, and scalable solution to global freshwater shortages, positioning it as a transformative technology in sustainable desalination.