Essential oils (EOs) have been recognized as eco-friendly promising insecticides for many important economic pests; thus, nano-formulations (NEs) of EOs have been formulated, developed, and evaluated to manage stored pests. The insecticidal activity of Origanum majorana L. essential oil (EO) and their nanoemulsion (NE) were evaluated against Callosobruchus maculatus and Callosobruchus chinensis. The chemical composition of this oil was identified using Gas Chromatography- Mass Spectrometry (GC/MS) analysis. Characterizations of formulated NE such as droplet sizes, polydispersity index (PDI), and zeta potential were determined. Our results revealed that the predominant compounds found in O. majorana L. were, 3-Cyclohexen-1-ol, 4-methyl-1-(1-methylethyl)-, (R)- (19.35%), γ-terpinene (11.79%) and α-terpinene (9.1%). The droplet sizes of NE O. majorana was 6.33 nm with PDI 0.498 and zeta potential showed a low negative charge (-5.19 mV). The results showed that EO and NE of O. majorana displayed the highest fumigant toxicity against C. chinensis adults with LC50 values (0.05 and 0.07 μLL-1 air), respectively after 3 days of exposure. In the case of seed treatment, EO and NE of O. majorana exhibited the highest toxicity in C. maculatus adults (LC50 = 207.51 and 220.36 mLkg-1). The complete inhibition of bruchid progeny and the full cowpeas protection were obtained by 2500 ml kg -1 of the tested EO and NE after 45 days. These findings indicate NE of O. majorana could be implemented in IPM of bruchids.