Abstract Objective Our objective was to examine potential differences in inflammatory markers, specifically antimicrobial peptide (AMP) LL-37 and interleukin-6 (IL-6), in the bloodstream of children with sepsis who had varying levels of vitamin D3. Methods A total of 59 pediatric patients diagnosed with sepsis from January 2021 to November 2021 were enrolled in this study. The pediatric patients with sepsis were categorized into three groups based on their levels of vitamin D3, and AMP LL-37, IL-6, and procalcitonin (PCT) were compared among the three groups. Discussion The LL-37 level in the group with vitamin D3 deficiency was notably lower than in the other two groups (p deficiency group vs. insufficiency group = 0.019, p deficiency group vs. normal group = 0.034), whereas the disparity between the group with vitamin D3 insufficiency and the group with normal vitamin D3 levels was not statistically significant. There was a positive correlation between the level of vitamin D3 and LL-37 in pediatric patients with sepsis (r = 0.324, p = 0.012). On the other hand, the level of IL-6 in pediatric patients with sepsis showed a positive correlation with both LL-37 (r = 0.474, p = 0.000) and PCT (r = 0.527, p = 0.000). Conclusion Pediatric patients with sepsis typically exhibit low levels of vitamin D3, which are positively correlated with the levels of serum LL-37. Furthermore, the presence of higher levels of serum LL-37 is positively correlated with higher levels of IL-6.