Thermal protective clothing (TPC) plays an important role in safeguarding firefighters exposed to high-temperature hazards. However, existing TPC systems lack the ability to address the comprehensive safety needs of working in a hazardous thermal environment. Limitations such as poor breathability, unstable insulation under different exposure conditions, and limited capability to mitigate carcinogenic particle exposure often contribute to heat stress, burn-related injuries, and cancer-related health effects among firefighters. In recent years, nanotechnology has attracted growing attention as a possible route toward more advanced TPC systems. Nanoscale materials offer significant pathways to engineer the thermal, moisture-management, and particle-filtration attributes of textile systems, making them highly relevant for improving TPC performance. This review analyzes current nanotechnology in terms of composition, processing, structure, properties, and performance. A total of 88 selected studies were reviewed and classified according to the nanosystem used to achieve relevant TPC functions. The performance domains investigated include flame retardancy, thermal management, moisture transport, filtration, and additional functions, to evaluate their potential for TPC applications. Nanotechnology can expand the TPC design space through multidomain protection and performance optimization; however, research remains largely fragmented. This review integrates findings and identifies design challenges and limitations, providing a coherent basis for comparing and guiding future TPC material design.