A series of isoxazoline derivatives containing diacylhydrazine moieties were designed and synthesized as potential insecticides. Most of these derivatives exhibited good insecticidal activities against Plutella xylostella, and some compounds exhibited excellent insecticidal activities against Spodoptera frugiperda. Especially, D14 showed outstanding insecticidal activity against P. xylostella (LC50 = 0.37 μg/mL), which was superior to that of ethiprole (LC50 = 2.84 μg/mL) and tebufenozide (LC50 = 15.3 μg/mL) and similar to that of fluxametamide (LC50 = 0.30 μg/mL). Remarkably, the insecticidal activity of D14 against S. frugiperda (LC50 = 1.72 μg/mL) was superior to that of chlorantraniliprole (LC50 = 3.64 μg/mL) and tebufenozide (LC50 = 60.5 μg/mL) but lower than that of fluxametamide (LC50 = 0.14 μg/mL). The results of electrophysiological experiments, molecular docking, and proteomics experiments indicate that compound D14 acts by interfering with the γ-aminobutyric acid receptor to control pests.