Nanofillers have emerged as a fascinating subject of interest in various industries due to their excellent mechanical and chemical properties. Their unique attributes, combined with high thermal stability, have sparked a remarkable advancement in the potential of catalysts used in chemical production. This chapter contains an in-depth and comprehensive exploration of the literature reports concerning the types of nanofillers used, with a specific focus on oxides and carbon-based nanofibers, 3D spatial properties, elucidating their intricate structures and configurations that play a pivotal role in their performance, as well as their impact on the stability and catalytic activity of nanofilled catalysts, as well as on the reaction mechanism. Through an in-depth analysis of these mechanisms, we hope to provide valuable insights that can further enhance the design and optimization of nanofilled catalysts, facilitating the development of more efficient and sustainable chemical production processes.