Background: Vitamin D may contribute to the balance in between regulatory and suppressive functions of T cells to modulate the inflammatory process in asthma. Objective: To assess serum vitamin D levels and their relationship with asthma control, asthma severity and its anti-inflammatory effect in children. Methods: This systematic review was based on articles published between 2009 and August 2022. Children under 18 years old with asthma were included. Results: The initial database search identified 2,015 manuscripts. Through screening identified only 25 eligible articles, but only eight studies met criteria for inclusion in the meta-analysis. The analysis revealed that in six studies involving 588 participants, mean 25-hydroxyvitamin D levels were lower in children with uncontrolled asthma compared to those with controlled asthma, with a mean difference of -5.07 (-8.57, -1.57) and a high rate of heterogeneity I ² = 89%. In five studies comprising 362 patients, the relationship between vitamin D and asthma severity was assessed. Lower levels of vitamin D were associated with a higher risk of severe asthma in children, with a mean difference of -6.00 (-8.09, -3.90) and substantial heterogeneity (90%, p<0.00001). In most patients, no significant correlation was found between vitamin D and lung function. Furthermore, serum vitamin D showed an association with interleukins and with regulatory T lymphocytes. Conclusion: Vitamin D plays a critical role in reducing asthma attacks. However, more randomized studies are necessary for a thorough evaluation and definitive recommendation for vitamin D supplementation.