Background: Polycystic Ovary Syndrome (PCOS) is one of the most prevalent endocrine disorders in reproductive-age women and carries a high burden of insulin resistance. Vitamin D deficiency, highly prevalent in Indian women, impairs pancreatic β-cell function and peripheral insulin receptor sensitivity, potentially worsening insulin resistance. Population-specific data from Central India examining this association in newly diagnosed PCOS women are scarce. Objectives: To assess serum vitamin D [25(OH)D] levels in newly diagnosed PCOS women, determine the prevalence of vitamin D deficiency, and establish its association and correlation with insulin resistance as assessed by HOMA-IR. Methods: A hospital-based, observational, cross-sectional study was conducted at Hamidia Hospital, Gandhi Medical College, Bhopal over 18 months. Sixty-six newly diagnosed PCOS women (Rotterdam criteria) were enrolled. Serum 25(OH)D was measured by competitive chemiluminescence immunoassay. HOMA-IR was calculated as [Fasting Insulin (µIU/mL) × Fasting Glucose (mg/dL)] / 405; values >2.5 indicated insulin resistance. Chi-square test, Student's t-test, and Pearson correlation were used. Results: Insulin resistance was present in 71.2% of participants. Vitamin D deficiency (<20 ng/mL) was detected in 80.3%; combined suboptimal vitamin D status was present in 93.9%. Vitamin D deficiency was significantly more prevalent in insulin-resistant women (87.2% vs 63.2%; p=0.047). Mean serum vitamin D was significantly lower in insulin-resistant women (15.06 ± 7.25 ng/mL) than non-insulin-resistant women (19.54 ± 10.15 ng/mL; p=0.017). HOMA-IR correlated negatively with serum vitamin D (r = −0.248, p=0.045). Conclusion: Vitamin D deficiency is near-universal in newly diagnosed PCOS women and is significantly associated with insulin resistance. Routine vitamin D screening and supplementation are warranted for early metabolic risk evaluation in PCOS.