The fall armyworm, Spodoptera frugiperda, is a newly introduced invasive pest in Egypt causing significant crop damage. In the invaded areas, fall armyworm management options are limited and primarily dependent on synthetic pesticides, raising concerns about resistance development and negative environmental and human health impacts. So, it was necessary to search for alternative solutions. Insect pathogenic viruses present a viable alternative as they are highly effective, host-specific, and have minimal harmful effects on beneficial insects and non-target organisms and promote sustainable agricultural practices. The primary objective of this research is to accurately identify the specific Nucleopolyhedrovirus NPV strain infecting fall armyworm larvae. This study identified naturally occurring Nucleopolyhedrovirus (NPV)-infected fall armyworm larvae. The NPV strain was isolated, purified, and examined microscopically. Scanning electron microscopy revealed a large quantity of polyhedra with varying shapes. Transmission electron microscopy of dissected larvae demonstrated the virus's significant impact on the cytoplasm and internal organs. Finally determining the exact NPV strain will aid in understanding its virulence and host specificity, and exploring the potential of integrating NPV with other control methods to enhance its effectiveness in sustainable agricultural practices.