Commercial pyrethroid insecticides use a high dosage that causes many side effects and accumulates as well. Nanoformulation has a promising efficacy in solving such fatal problems. Four commercial pyrethroid insecticides (Axon, Spanner, Cyperco, and Karilot) were formulated into nanoemulsions using the two-phase method. Nanoemulsion stability was checked and characterized using DLS and transmission electron microscopy (TEM) and tested for their physicochemical properties. The insecticidal efficiency of both the commercial and nanoemulsion insecticides was evaluated against Spodoptera littoralis under laboratory and field conditions. The cytotoxicity of the most effective commercial and nanoemulsion insecticides was also checked on normal human skin cells (BJ1). The nanoemulsions demonstrated good stability and had mean droplet sizes ranging from 166.7 to 221.7 nm. The nanoemulsions also exhibited higher insecticidal activity against Spodoptera littoralis, with lower LC50 (166.93–226.24 mg/L) and LC90 (284.11–336.65 mg/L) values and a higher percentage of decrease in the larval population (77.5–86.5%) than the commercial insecticides. The nanoformulations of Axon and Spanner were the most effective insecticides. The commercial and nanoformulations of Axon did not harm normal human cells at concentrations below 500 µg/mL. The study demonstrates that nano insecticides can be considered as potential replacements for conventional insecticides. Indeed, this study highlights the potential of nano-insecticides as efficient and safer alternatives to conventional formulations for pest management.