Background: Vitamin D plays essential roles in calcium homeostasis, immune modulation, and inflammatory regulation, suggesting potential implications for periodontal health. Adolescence represents a critical period for both skeletal development and establishment of periodontal health patterns, yet research examining vitamin D–periodontal relationships in this population remains limited. Objective: This study aimed to investigate the correlation between serum vitamin D levels and periodontal health parameters among adolescents, exploring potential associations with gingivitis severity and clinical attachment status. Methods: A cross-sectional analytical study was conducted among 486 adolescents aged 12–17 years. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured using chemiluminescent immunoassay. Periodontal assessment included plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL). Participants were categorized by vitamin D status: deficient (<20 ng/mL), insufficient (20–29 ng/mL), and sufficient (≥30 ng/mL). Pearson correlation, ANOVA, and multivariable regression analyses evaluated associations. Results: Mean serum 25(OH)D was 24.67 ± 9.84 ng/mL, with 31.5% classified as deficient, 38.9% as insufficient, and 29.6% as sufficient. Vitamin D-deficient adolescents demonstrated significantly higher mean GI (1.67 ± 0.48) compared to sufficient participants (1.12 ± 0.39; p<0.001). Significant negative correlations were observed between 25(OH)D and GI (r=-0.412, p<0.001), BOP (r=-0.387, p<0.001), and PI (r=-0.298, p<0.001). Multivariable regression confirmed vitamin D deficiency as independently associated with gingivitis (OR=2.34; 95% CI: 1.56–3.51; p<0.001) after adjusting for confounders. Conclusion: Vitamin D levels demonstrate a significant inverse correlation with periodontal inflammation markers in adolescents. Vitamin D deficiency is independently associated with increased gingivitis severity, suggesting potential benefits of adequate vitamin D status for adolescent periodontal health.