Background <p>Vitamin D may play a role in cardiovascular health, particularly in lipid metabolism and atherosclerosis. This study examines the correlation between serum vitamin D levels with Apolipoprotein B (Apo B), and the Framingham Risk Score (FRS) and evaluates the impact of correcting severe vitamin D deficiency on Apo B levels and FRS among a group of Iraqi population.</p> Methods <p>This two-phase study was conducted in Baghdad between November 2022 and October 2023 and included a cross-sectional phase examining the association between vitamin D, with Apo B, and the FRS, followed by a prospective phase assessing the impacts of vitamin D correction. A total of 201 participants were recruited, including 60 individuals with severe vitamin D deficiency (≤ 10 ng/ml) who received supplementation and 40 with sufficient vitamin D levels (≥ 30 ng/ml) serving as controls. Levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), Apo B, and FRS were evaluated at baseline and after six months. The Thai Clinical Trials Registry (TCTR) has retrospectively registered and approved the study under the identification number TCTR20250301003 on the 1st of March 2025.</p> Results <p>Vitamin D levels correlated significantly with age (<i>p</i> &lt; 0.001), Apo B (<i>p</i> = 0.007), and FRS (<i>p</i> = 0.003) in the cross-sectional phase. After supplementation TC (<i>p</i> = 0.004) and FRS (<i>p</i> = 0.007) significantly decreased in the treatment group, with no significant changes in Apo B. Males only showed significant decrease in FRS and TC.</p> Conclusion <p>Vitamin D correction significantly decreased TC and FRS reinforcing its role in lipid metabolism and cardiovascular health. However, Apo B levels remained unchanged, suggesting that vitamin D may not directly influence Apo B metabolism in the short term. These findings emphasize the importance of correcting severe vitamin D deficiency before calculating FRS due to its impact on lipid parameters.</p>