The present study, emphasis on the encapsulation of Ocimum basilicum L. leaf essential oil by utilizing Polysorbate 80 and its evaluation of antibacterial (MIC), antioxidants and larvicidal activity against C. quinquefasciatus. After the encapsulation, nanoemulsion characterized by using a Zeta potential analyzer and Scanning Electron Microscope (SEM). Nanoemulsion was exhibited significantly more antibacterial activity (MIC) against different enteric bacterial pathogens, Enterococcus faecalis (MTCC-2729), Staphylococcus aureus (MTCC-441), Salmonella paratyphi (MTCC-735), Klebsiella pneumoniae (MTCC-432) and antioxidant ability of the formulated nanoemulsion and essential oil was tested and results of DPPH, Hydroxyl radical scavenging activity, Superoxide scavenging activity and FRAP activities exhibits highest antioxidant activity. The larvicidal activities of C. quinquefasciatus larva was observed at 24 h exposure period and significant mortality were observed after the treatments of essential oil II instar larvae have the maximum mortality at 100 ppm (91.07 ± 0.57) and nanoemulsion (96.87 ± 0.55). The III instar larvae maximum mortality was observed at 24 h exposure period in essential oil at 100 ppm (88.95 ± 0.80) and nanoemulsion (93.89 ± 0.55). These results proposed for developed plant essential oil based nanoemulsion is thermodynamically stable and formulated nanoemulsion will be used for various biomedical applications, food industry and will be drug delivery against the mosquito vector control.