Background <p>The growing awareness of the harmful effects of chemical fungicides resulted in the increasing demand for natural and sustainable alternatives for treatment of fungi-infected plants. This study focuses on the green biosynthesis of silver nanoparticles (AHNPs) using the aqueous extract from the nutshell of <i>Arachis hypogaea</i>, a common bio-waste.</p> Results <p>The synthesized green silver nanoparticles were characterized using UV–Vis spectroscopy, dynamic light scattering (DLS), zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The antifungal activity was analyzed by assessing the synthesized silver nanoparticles in two pathogenic strains of <i>Aspergillus niger</i>. The synthesized silver nanoparticles reduced the growth of <i>Aspergillus niger</i> strain 1 and 2 by 46.25% and 75.29%, respectively, at 100 µg/mL.</p> Conclusions <p>The study proves that the silver nanoparticles synthesized using <i>Arachis hypogaea</i> nutshell extract is effective in controlling the fungal pathogens. Further research will be carried out to analyze the antifungal activity in field condition and can be developed into nano-based fungicides for commercial applications. Nano-based fungicides are eco-friendly and can be tailor made to suit the farmers need to achieve sustainable agriculture.</p> Graphical abstract <p></p>