Biological pest control is increasingly crucial and emphasized in research, leading to the frequent use of entomopathogenic fungi such as Beauveria bassiana and B. brongniartii. Integrated pest management often requires multiple control agents to address various species simultaneously, raising the question of the interaction between the utilized fungi and the other active agents applied simultaneously. The present study examined the interactions between active ingredients and entomopathogenic fungi in laboratory conditions. The results indicate that insecticides and herbicides containing diazinon or glyphosate have neutral or positive effects on the examined Beauveria species. However, fungicides with the active ingredients penconazole or sulfur demonstrated adverse effects when used alongside the tested entomopathogenic fungi. The combined use of fungicides and fungi deserves examination because, in many cases, fungal diseases appear simultaneously with pests, e.g., powdery mildew.