The chemical composition of essential oil obtained by hydrodistillation of the leaves of Pachira glabra Pasq., (PgEO) has been studied by Gas Chromatography (GC) and Gas Chromatography coupled with Mass Spectrometry (GC/MS). Thirty three constituents representing 98.4% of total contents were identified from the essential oil. The major constituents of oil were limonene (23.2%), β-caryophyllene (14.5%), phtyol (8.5%) and β-bisabolene (6.3%). The antimicrobial activity of the PgEO was evaluated against a panel of ten bacteria and three fungal strain using agar diffusion and broth microdilution methods. Results have shown that the PgEO exhibited moderate to strong antimicrobial activity against the tested microorganisms except Citrobacter youagae, Micrococcus spp. and Proteus spp. The activity zones of inhibition (ZI) and minimum inhibitory concentrations (MIC) ranged between 13.7 mm-24.0 mm and 0.3 mg/mL-2.5 mg/mL, respectively. The insecticidal activity of PgEO was assayed against the adult Sitophilus zeamais. The lethal concentrations (LC50 and LC90) of the PgEO showed it to be toxic against adult S. zeamais at 32.2 and 53.7 mg/mL, respectively. This is the first report on the chemical composition and in vitro biological activities of essential oil of P. glabra growing in Nigeria.