The fall armyworm (Spodoptera frugiperda) has become the major biotic constraint on maize production in Cameroon, causing yield losses of 15 to 78 %. Given the limitations of synthetic insecticides (cost, toxicity and the development of resistance), this study evaluated the insecticidal potential of Thevetia peruviana seed and leaf aqueous extracts in controlling S. frugiperda, both in the laboratory and in the field. The extracts were obtained by macerating 250 g of ground seeds or leaves in 5 L of water for 24 hours. In the laboratory, the extracts were applied by direct contact at three concentrations (25, 50, and 100 mg/mL) to group of 10 larvae. Insecticidal activity was assessed based on larval mortality recorded 24 hours after treatment, and monitored over 5 days. In the field, a split-plot design with four replicates compared four treatments control, seed extract (50 g/L), synthetic insecticide (1.66 mL/L), and leaf extract (50 g/L) on two maize varieties (CMS 8704 and a local variety) over two consecutive growing seasons. The aqueous seed extract at concentrations of 50 and 100 mg/mL caused 100% larval mortality as early as 24 hours after exposure, a result comparable to that of the synthetic insecticide, whereas the leaf extract produced no mortality at that time point (0%). However, larval mortality induced by the leaf extract reached 46.66% five days after application. In the field, the fall armyworm larval density on maize plants treated with the aqueous seed extract of T. peruviana was reduced by 100%, matching the performance of the synthetic insecticide, and by 51.85% and 44.44% on plants treated with the aqueous leaf extract during the first and second growing seasons, respectively. Substantial maize yield gains were recorded for the V1 variety (CMS 8704) in plots treated with the aqueous seed extract of T. peruviana (5 t/ha) and in those treated with the aqueous leaf extract of T. peruviana (2.75 t/ha), compared to the untreated control plots (1.25 t/ha) during the second growing season. These findings demonstrate that aqueous extracts of T. peruviana exhibit insecticidal efficacy comparable to that of synthetic insecticides and represent a promising botanical alternative for the management of S. frugiperda in maize.