: This study aimed to investigate the long-term effects of maternal exposure to fine particulate matter (PM) with or without vitamin D supplementation on the renal microvasculature in adult rat offspring. : Pregnant Sprague-Dawley rats were exposed to normal saline, PM, and PM with vitamin D for one month during nephrogenesis. Male offspring kidneys were taken for analyses on postnatal day 56. : Adult offspring rats exposed to maternal PM exhibited lower body weights and greater glomerular and tubular injury scores compared to control rats. Semi-quantitative analysis revealed a significant reduction in glomerular and peritubular capillary endothelial cells, along with a decrease in the number of glomeruli in the PM group. Maternal vitamin D supplementation reduced these changes. In offspring rats exposed to maternal PM, intrarenal expression of renin, angiotensin-converting enzyme (ACE), cytochrome P450 27B1, and vascular endothelial growth factor-A (VEGF-A) increased, while expression of the vitamin D receptor, Klotho, VEGF receptor 2, angiopoietin-1, and Tie-2 decreased. Maternal vitamin D supplementation restored VEGF receptor 2 and angiopoietin-1 activities and reduced ACE and VEGF-A protein expression in adult offspring kidneys. : Early-life exposure to PM may lead to long-term alterations in renal microvasculature and nephron loss. Maternal vitamin D supplementation during renal development can ameliorate PM-induced capillary rarefaction and nephron loss in the kidneys of adult offspring.