Because of their negative effects on the environment, humans, and other organisms, chemical pesticides have been prohibited in many countries. Alternative microbial management is easy-to-implement, effective, and safe for humans and the environment. Fungus-based biopesticide products like kojic acid could commercialize as effective alternative chemical pesticides. Aspergillus oryzae ASU44 (OL314732) was isolated from hollyhock rhizosphere and identified using 18S rRNA gene sequencing. The strain showed high ability of kojic acid production especially after optimizing the production using 41-run Box-Behnken statistical design. Maximum kojic acid production was 46.53 g/l (predicted values 46.62 g/l) obtained in run number (23) using Glucose (150, g/l), Yeast extract (5 g/l), KH2PO4 (3 g/l), MgSO4.7H2O (0.5 g/l) and pH (3). The design was effective to applied with coefficient (R2) 0.988, 0.986 (adjusted R2 0.975, 0.972) for kojic acid (g/l) and dry fungal mass formation (g/l). The pathogenicity of the fungus and their kojic acid in addition to standard synthetic kojic acid was investigated to the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae). All treatments had a considerable impact on aphid mortality. The mortality rate was relative to the duration of exposure and the quantities of bio-pesticides agents. However, data revealed that as concentrations increased, the lethal time values decreased . Aspergillus oryzae ASU44 and its extract containing kojic acid were found effective against A. gossypii. As a result, this research suggests that these agents could be effective in aphid cotton management.