The present study aims to investigate the protective role of L-Carnitine (LC) against Deltamethrin-induced testicular toxicity in male rats exposed during their early developmental period. DTM was administered at a dose of 6 mg/kg body weight to the prepubertal rat’s Post-Natal Day (PND) 23 rats through oral route and exposure was continued until they reach PND 90. After completion of the exposure period, male rats were assessed for reproductive endpoints. Deltamethrin exposure caused a significant reduction in testosterone production and decreased the sperm parameters such as sperm count, sperm motility, sperm viability and sperm membrane integrity. Deltamethrin intoxication also reduced the reproductive organs’ weight and testicular steroidogenic enzymes (3β-hydroxysteriod dehydrogenase and 17β-hydroxysteriod dehydrogenase) levels. Further DTM exposure induced the oxidative stress as evidenced by the significant reduction in the superoxide dismutase, catalase, and glutathione levels with significant elevation in the malondialdehyde. DTM also induced the significant sperm DNA damage. In addition, DTM exposure significantly declined the testosterone levels over the control group, indicating the impaired steroidogenesis. In addition to the compromised steroidogenesis DTM exposure also deteriorated the testicular architecture according to the histological observations. On the other hand, therapy with LC (100 mg/kg body weight) improved the biomass of reproductive organs, the features of the sperm, testicular steroidogenesis and testicular antioxidant enzymes levels. Concluding that DTM might disturb the testicular antioxidant level that eventually impaired the reproductive health of rats. However, LC supplementation mitigated the reproductive toxicity through its antioxidant property.