Background: Oligohydramnios, characterized by a low Amniotic Fluid Index (AFI), is associated with adverse pregnancy outcomes, including fetal growth restriction, preterm labor, and low birth weight. Effective interventions for improving AFI are critical, particularly in resource-limited settings. L-Arginine, a nitric oxide precursor, has shown promise in enhancing uteroplacental circulation and increasing AFI. This study aimed to evaluate the efficacy of L-Arginine supplementation in improving AFI and associated maternal and neonatal outcomes in pregnant women with oligohydramnios in Bangladesh. Methods: This study was conducted at Islami Bank Hospital over one year (July 2023 to June 2024), involving 90 pregnant women diagnosed with oligohydramnios. Participants received daily L-Arginine supplementation, and AFI was measured before and after the intervention. Maternal and neonatal outcomes, including gestational age at delivery, birth weight, and neonatal intensive care unit (NICU) admissions, were recorded. Statistical analysis was performed using paired t-tests, with p < 0.05 considered statistically significant. Results: The mean AFI increased significantly from 5.4 cm (SD ±1.7) before the intervention to 8.6 cm (SD ±2.1) after supplementation, with a mean difference of 3.2 cm (p < 0.001). Low birth weight was observed in 20% of the neonates, while 17.78% required NICU admission. There was a notable improvement in neonatal outcomes with L-Arginine supplementation. Conclusion: L-Arginine supplementation significantly improved AFI and neonatal outcomes, making it a viable intervention for managing oligohydramnios in pregnant women. Further research is recommended to confirm these findings in larger populations.