Catalysis plays a crucial role in both industrial and environmental processes by improving reaction rates and selectivity. This chapter examines the integration of catalysts with nanofillers, their development into bio-nanofillers, and the benefits of bio-nanofillers, such as increased biocompatibility and sustainability. It offers an in-depth analysis of bio-nanofillers, covering various synthesis methods and the mechanisms that enhance catalytic performance. Additionally, it explores how bio-nanofiller catalysts impact factors like reaction kinetics, selectivity, and yield. Characterizing bio-nanofillers is essential to assess their compatibility with catalysts. Therefore, this chapter also covers various characterization techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, and nuclear magnetic resonance spectroscopy (NMR). It further highlights the applications of bio-nanofillers in industrial and environmental contexts, focusing on their use in chemical synthesis, energy production, pharmaceuticals, pollution control, wastewater treatment, etc. Additionally, it addresses current challenges associated with bio-nanofiller, including issues of stability, reusability, scalability, and cost. It concludes with an overview of future research directions, emerging materials, and innovative approaches, reflecting on how bio-nanofillers are advancing catalytic processes.