Seeking to find innovative technologies and treatments to eradicate pathogenic fungi that pose a hazard to human health has been a global problem given their antibiotic resistance. Currently, using silver nanoparticles that are antifungal in biocontrol methods is giving us a possible way to deal with this problem. Because metal nanoparticles have a high surface area to volume ratio, they have potent antimicrobial capabilities. This article describes a new, simple, and long-lasting way to use Brevibacillus sp. supernatants to make antifungal silver nanoparticles. We explored the microbiological composition of these nanoparticles. The AgNPs that were made had a peak absorption spectrum at 420 nm and a size range of 30.12 to 38.59 nm, as shown by spectroscopic and microscopic analysis. In vitro tests showed strong antifungal activity against Aspergillus ochraceus and Alternaria alternata, stopping the growth of colonies by 73.5% and 59%, respectively, compared to controls., reducing colony growth by 73.5% and 59%, respectively, compared to controls. This study shows that silver nanoparticles made by Brevibacillus sp. might be useful for fighting fungal diseases and environmental fungal contaminants. They could be a new way to deal with the worldwide problem of fungal infections.