The rapid advancements in silica extraction techniques from biomass have led to the significant utilization of silica across various industries. Among the world’s essential crops, rice stands out as a primary source of carbohydrates for human consumption. Within rice cultivation, rice husk emerges as a prominent agro-residue, containing substantial quantities of silicate. This chapter offers an encompassing review of the methodologies employed to produce nano silica from rice husk, covering both thermal and chemical extraction approaches. The discourse extends to proposing an optimal and sustainable extraction methodology for nano silica. Furthermore, this chapter delves into the techniques involved in preparing nanofluids, considering their intended applications. The focus lies in establishing a coherent link between nano silica and nanofluids, elucidating how these two components synergize for specific end uses. Notably, the implications of nanoparticle integration within nanofluids are examined concerning crucial aspects such as thermal conductivity, rheological behavior, and overall stability. This exposition does not stop at technical considerations but extends to exploring the vast expanse of potential applications for silica nanofluids. The domains of solar energy harnessing, automotive engineering, electronics cooling, and even biomedical applications are contemplated, each offering a unique platform for the incorporation of silica nanofluids to enhance performance and efficiency.