Background: Psoriasis is a chronic, immune-mediated skin disorder influenced by environmental and metabolic factors, including vitamin D status. Vitamin D plays a key role in immune regulation and keratinocyte proliferation, both central to psoriasis pathogenesis. Objective: To evaluate serum vitamin D levels in psoriasis patients and assess their association with disease severity. Methods: A cross-sectional study was conducted on 100 clinically diagnosed psoriasis patients. Demographic details, clinical characteristics, and sun exposure patterns were recorded. Serum 25(OH) vitamin D levels were measured and psoriasis severity was assessed using the Psoriasis Area and Severity Index (PASI). Statistical analysis included correlation and ANOVA to evaluate associations between vitamin D levels and PASI scores. Results: The study population consisted of 59% males and 41% females, with the majority (34%) aged between 31–45 years. Plaque psoriasis was the most common type (68%), and 48% had the disease for 1–5 years. Vitamin D levels were insufficient in 51%, sufficient in 39%, and deficient in 10% of patients. A statistically significant inverse correlation was observed between vitamin D levels and psoriasis severity (r = -0.68, p < 0.001). Patients with mild psoriasis had the highest mean vitamin D levels (33.84 ng/mL), while those with severe psoriasis had the lowest (14.48 ng/mL). Conclusion: Vitamin D insufficiency is common among psoriasis patients and is significantly associated with greater disease severity. Routine screening and correction of vitamin D levels may benefit the overall management of psoriasis.