Mango hopper (Amritodus atkinsoni Lethierry) causes devastations in the early vegetative stage of the mango crop. The classical management of mango hopper is with systemic insecticides but their overuse has caused environmental pollution. Here, we have evaluated the entomopathogenic role of Clonostachys rosea through bioassay and optimized media for its large-scale culturing. The current study reveals the potentiality of C. rosea as entomopathogenic on A. atkinsoni. Initially, morphological and molecular characterization was used to validate local isolates’ identity as C. rosea. Further, we have evaluated the entomopathogenic role of C. rosea through a bioassay, where the highest mean mortality in A. atkinsoni was observed at a treatment concentration of 3 × 108 conidia/mL, with 96.67% mortality after 168 h of infection. This work also provides insight into the laboratory-based media standardization for C. rosea, resulting in oatmeal agar media and broth as the most suitable artificial media, and 20 °C temperature for its mass culture. Thus, C. rosea is a novo-entomopathogenic fungus on A. atkinsoni and has a high potency to be included in the management of mango hopper pests.