The growing prevalence of electromagnetic interference (EMI), driven by the widespread use of electronic and wireless devices, has created an urgent need for lightweight, flexible, and efficient shielding materials. This chapter presents an in-depth yet accessible overview of how nanoparticles—engineered materials with dimensions on the nanometer scale—are being integrated into textiles to create advanced EMI shielding solutions. Various types of nanoparticles, including metal-based (e.g., silver, copper), metal oxides (e.g., titanium dioxide, iron oxide), and carbon-based materials (e.g., graphene, carbon nanotubes), are examined for their unique electromagnetic, conductive, and structural properties. The chapter also outlines key fabrication techniques such as dip-coating, electrospinning, in-situ chemical synthesis, and fiber integration, which allow for precise incorporation of nanoparticles into fabrics without compromising comfort or flexibility. Applications span multiple sectors, including healthcare, defense, aerospace, and consumer electronics, where such textiles enhance both safety and device performance. In addition to technical performance metrics like shielding effectiveness and durability, the chapter addresses important interdisciplinary concerns such as nanoparticle toxicity, environmental impact, and economic scalability. Emerging trends such as smart textiles capable of adapting to environmental changes, and the development of biodegradable or eco-friendly nanomaterials, are also discussed. This chapter offers a comprehensive and approachable entry point for researchers, engineers, and policy-makers interested in the intersection of nanotechnology, textile engineering, and electromagnetic safety.