AIM: Vitamin D is involved in several processes related to the development of neuronal and non-neuronal cells. There is a possible link between maternal vitamin D status in pregnancy and delayed neurocognitive development in the offspring. The aim of the study was to explore the association of maternal and cord blood vitamin D levels with infants' neurodevelopment at 6 and 9 months of age. METHODOLOGY: A cohort study was conducted in western Rajasthan, India. Maternal and cord blood samples were collected at the time of delivery. Serum 25(OH)-vitamin D levels were measured in both. Infant neurodevelopment was assessed at 6 and 9 months of age in six domains namely cognitive, receptive language, expressive language, fine motor, gross motor and social-emotional using the Bayley Scale of Infant Development- III (BSID-III). RESULTS: A total of 175 mother-child pairs were enrolled. Among the mothers taking part in this study, 7.3% had deficient and 59.09% had insufficient levels of serum 25(OH) vitamin D during the third trimester of their pregnancy. Maternal and cord blood serum 25-OH vitamin D levels were 18.86 ± 8.53 ng/mL and 17.39 ± 8.87 ng/mL, respectively, and there was a significant correlation (r = 0.9778, CONCLUSION: Maternal and cord serum 25-OH vitamin D deficiency was significantly associated with the cognitive and social-emotional development of infants.