Background: Adolescence is the phase of rapid transition of the body. The requirement of all minerals and vitamins changes in this phase of life so does Vitamin D. Despite Vitamin D being abundantly available, its deficiency, which can cause innumerable side effects on the body, is extremely common among the general population.Material and methods: The present study was a cross-sectional study carried out from January 2021 to July 2022 for two years at various government rural high schools in Kolar, Karnataka, India. All adolescents who were aged 11-18 years and studying in 9 th and 10 th standards were included in the study after consent and assent. Adolescent boys and girls with any pre-existing mental health illness were excluded from the study. To assess depression, Beck's Depression Inventory (BDI-II) was used. Vitamin D3 levels were assessed by using VITROS Immunodiagnostic products using a 25-OH Total reagent pack. All data were entered in a Microsoft Excel sheet (Redmond, USA) and analyzed using IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp. To check for the association between factors, Chi-square was applied with a level of significance defined as a p-value less than 0.05.Results: Out of 451 students, 272 (60.3%) belonged to the 15-year age group, 224 (49.7%) were boys, 235 (52.1%) were studying in 10 th standard, 323 (71.6 %) belonged to nuclear families, 379 (84%) were nonvegetarian by diet, 222 (49.2%) had sun exposure in the afternoon, and 156 (34.6%) had a sun exposure of fewer than 60 minutes, 133 (29.5%) had severe depression according to Beck's Depression Inventory-II. One hundred sixty-two (35.9%) had insufficient Vitamin D3 levels (12-20 ng/ml), and 66 (14.6%) had deficient levels of Vitamin D3 (less than 12 ng/dl). There was a statistically significant association between depression and Vitamin D3 levels.Conclusion: There are innumerable causes of adolescent depression. The present study shows Vitamin D levels were statistically associated with depression among adolescents. Vitamin D supplementation of at least 600 international units, which is the recommended dietary allowance (RDA), could be beneficial in tackling Vitamin D to sufficiency status (20-100 ng/ml) and also indirectly address Adolescent Depression. Better study designs, like randomized control trials showing Vitamin D intervention and its possible curative role in adolescent depression, are required to establish the causal association.