Background: Vitamin D deficiency is increasingly recognized as a global public health concern and has been implicated in the development of several cardiovascular disorders. Besides its established role in bone metabolism, vitamin D influences endothelial function, inflammation, vascular smooth muscle proliferation, insulin sensitivity, and activation of the renin-angiotensin-aldosterone system. Deficiency may therefore contribute to an increased risk of cardiovascular disease (CVD).Objective: To evaluate the association between vitamin D deficiency and cardiovascular disease risk among adult patients attending a tertiary care hospital.Methods: A hospital-based cross-sectional study was conducted among 300 adults aged 30–80 years. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured and categorized as deficient (<20 ng/mL), insufficient (20–29 ng/mL), and sufficient (≥30 ng/mL). Cardiovascular risk factors, biochemical parameters, electrocardiographic findings, and cardiovascular events were analyzed. Multivariate logistic regression identified independent predictors of cardiovascular disease.Results: Vitamin D deficiency was identified in 176 (58.7%) participants, insufficiency in 74 (24.7%), and sufficient levels in 50 (16.6%). Cardiovascular disease was significantly more prevalent among vitamin D-deficient individuals (39.8%) than among those with sufficient vitamin D levels (14.0%, p<0.001). Hypertension, diabetes mellitus, dyslipidemia, obesity, and elevated inflammatory markers were significantly associated with vitamin D deficiency. After adjustment for confounding variables, vitamin D deficiency remained an independent predictor of cardiovascular disease (Adjusted OR=2.61; 95% CI:1.48–4.59).Conclusion: Vitamin D deficiency is strongly associated with increased cardiovascular disease risk. Routine screening of high-risk individuals and timely correction of deficiency may contribute to improved cardiovascular health.