Rapid growth of electronic devices and communication systems in the modern age demands potential electromagnetic shielding materials that can mitigate the negative effect of electromagnetic interference (EMI) which can degrade the performance of sensitive equipment and communication systems due to unwanted interference of electromagnetic radiation. Nanomaterials and composites, with their unique properties, have emerged as promising candidates for EMI shielding due to their superior electrical conductivity, dielectric properties, magnetic response, structural integrity, and tunable characteristics. Specifically, carbon-based nanomaterials such as carbon nanotubes (CNTs) and graphene systems, metal nanoparticles, metal–organic frameworks (MOFs), MXenes, and conductive polymers, each of which contributes unique characteristics to the shielding effectiveness and mechanical properties. These materials have achieved enhancements in shielding effectiveness of up to 40–70 dB. This extends to the nanocomposites in which polymers, ceramics, and metals fortified with the power of nanomaterials can significantly improve the mechanical strength and flexibility of the nanocomposite while maintaining high shielding effectiveness. Hybrid nanocomposites are analyzed for their combined effects in enhancing electromagnetic interference (EMI) shielding performance. Furthermore, preparation methods like solution blending, electrospinning, and 3D printing are cost effective over the structure and alignment of nanomaterials within the composites, thereby improving shielding effectiveness without compromising mechanical integrity. The orientation of nanomaterials has a crucial role in assigning the overall material properties. This chapter, therefore, highlights the pivotal role of nanomaterials and their composites in fabricating next-generation EMI shielding materials, with an emphasis on attenuation mechanisms, material characteristics, and their incorporation into composite structures.