Nanotechnological applications involving the fabrication of potential nanomaterials and novel strategies for mitigation of contaminants have helped a lot in environmental cleanup. The chemical route for silica nanoparticle (NPs) synthesis using tetra ethyl oxy silicone and tetramethyl oxy silicone is expensive and energy intensive. Silica NPs synthesis from coal fly ash waste could prove to be economical. In this study, the investigators have used coal fly ash for silica NPs synthesis via a noble and economical approach. This biosynthetic approach involved two steps: (1) extraction of crude sodium silicate by using alkali treatment of fly ash and (2) the addition of crude sodium silicate to the supernatant of Fusarium oxysporum for fabrication of silica NPs. The developed silica NPs are analyzed by the analytical instruments where the microscopic techniques revealed 10–50 nm‐sized floral‐shaped mycogenic silica NPs. The X‐ray diffraction revealed the amorphous nature of the silica NPs with a broad spectrum starting from 8º and ending at 23º having centered at 13.1°. Fourier transform infrared spectroscopy, in region 400–1200 cm−1, exhibited three distinguishing bands for silica NPs. The current study reports a novel and effective method for the development of silica NPs with a high yield and purity of about 95%.