Background and objective Urinary tract infection (UTI) is one of the common causes of febrile illness in young children. Vitamin D influences the levels of endogenous cathelicidin, an antimicrobial peptide, which improves bladder wall immunity and prevents UTIs. In light of this, we conducted this study to determine the association between vitamin D deficiency and UTIs in children and to identify whether vitamin D deficiency is one of the risk factors for UTIs. Materials and methods This was a case-control study of children aged between one to five years. Eighty-two children with the first episode of febrile culture-proven UTI as cases and 82 healthy children as a control group were included in this study. The sera were analyzed for 25-hydroxy vitamin D levels and classified as vitamin-D deficient if their level was below 30 ng/mL. Descriptive statistics were presented as numbers and percentages. Continuous data were expressed as means and standard deviations (SD). Pearson's chi-square test was used to test the significance of the differences in variables between the two groups. Multiple logistic regression equation methods were used to predict the relationship between the dependent and independent variables. Results The mean age of the study and the control group was 2.36 ±1.42 years and 2.57 ±1.26 years, respectively. The mean serum 25-hydroxy vitamin D levels in the patients and controls were 24.27 ±9.70 ng/mL and 31.97 ±10.7 ng/mL (p<0.001), respectively. Vitamin D deficiency was present in 34 (41.5%) patients and 10 (2.2%) in the control group (p<0.001). Conclusion Based on our findings, vitamin D deficiency might be one of the risk factors for UTIs in children. Vitamin D deficiency is significantly associated with febrile UTIs in children between one to five years of age.