The study analyzed 115 hospitalized patients with alcoholic liver disease (ALD) between 2021 and 2024, where vitamin D deficiency (serum 25(OH)D < 20 ng/ml) was present in 35.7% of patients. Vitamin D deficiency was associated with alcoholic hepatitis, cirrhosis, ascites, sarcopenia, elevated total bilirubin, MELD score, and Maddrey's discriminant function ≥ 32 after adjustment for season (all p < 0.05). In multivariable logistic regression, it independently predicted greater disease severity (OR 3.087, 95% CI 1.034–9.215; p = 0.043). Kaplan-Meier analysis showed reduced survival in deficient patients (log-rank p = 0.025), and multivariable Cox regression confirmed it as an independent predictor of mortality (HR 3.179, 95% CI 1.064–9.500; p = 0.038). ROC analyzes w indicated optimal 25(OH)D cut-off values of 22.74 ng/ml for sarcopenia and 14.2 ng/ml for spontaneous bacterial peritonitis (SBP). Vitamin D deficiency was associated with greater disease severity, reduced survival, and increased risk of sarcopenia and SBP. The findings are exploratory due to the retrospective design, limited number of events, and short follow-up and require confirmation in prospective studies.