The current scenario in developing various products is profoundly affected by nanoparticle utilization. The use of nanofillers in composite product production is one example of a novel approach to developing nanoparticles. Nanosized active fillers can immobilize neighboring molecule groups and provide a possible orientation for the polymer material, filling a particular volume and disrupting the conformational position of a polymer matrix. As a reinforcement or matrix in composite production, these nanofillers profoundly affect the final composites and mechanical properties. Nanofillers are solid additives with a different composition and structure than the polymer matrix. They are mostly made of inorganic substances with occasional traces of organic ones. Nanosized fillers can be made from a wide variety of materials, including clays (like Montmorillonite (MMT)), natural biopolymers (like chitosan), natural antimicrobial agents (like nisin, grape seed extract), metals (like silver), and metal oxides (e.g., ZnO, CuO, TiO2). Nanofiller applications based on thermal properties are widely used in various industries, including transportation, medicine, sports, aerospace, etc. This chapter aims to summarize the latest type of composites using a wide range of nanofillers, all covered in detail.