Deltamethrin is a widely used synthetic pyrethroid insecticide for controlling cowpea pod borers; however, its persistence in crops and soil may raise environmental and food safety concerns. In this study, deltamethrin residues in cowpea pods, leaves and soil were quantified using gas chromatography to evaluate their persistence under field conditions. The half-life of deltamethrin in cowpea pods ranged from 1.73 days at the recommended dose (RD) to 3.15 days at the double dose (DD). Similarly, the half-life ranged from 1.65–1.51 days in leaves and 1.86–1.71 days in soil for RD and DD, respectively. Dietary risk assessment indicated that residue levels in pods exceeded the maximum permissible intake (MPI) of 0.60 mg person-1 day-1 on some sampling days. However, due to rapid degradation and short persistence, deltamethrin can be considered relatively safe when applied at RDs in the cowpea ecosystem.