This study aimed to: (1) isolate entomopathogenic fungi from infected host insects; (2) conduct bioassay of different entomopathogenic fungi (EPF) isolates against the cucurbit leafworm, Diaphania indica.; and (3) identify the most potential EPF isolate using morphological and molecular characterization. Four entomopathogenic fungi isolates that showed positive infection to D. indica larvae were evaluated. The most virulent isolate was subjected to morphological and molecular characterization. Results showed that EPF Isolate 1 is highly virulent to D. indica larvae with 97.5-100% mortality in the 2nd to 4th instar larvae. EPF Isolate 1 was first to show infection 1.38±0.41 days after inoculation, and larvae were entirely covered with white mycelia 5.25±0.41 days. Molecular identification revealed the isolate as Isaria fumosorosea as indicated by molecular marker internal transcribed space region of 5.8s (ITS-5.8s) ribosomal DNA. EPF Isolate 1 was identified as Isaria fomosorosea. It is the most virulent and potential isolate against cucurbit leafworm, D. indica.