Proper posture, characterized by the appropriate alignment of the cervical, thoracic, and lumbar segments of the spine, enables these regions to maintain their normal curvature. Body composition is recognized as one of the factors that can influence overall postural alignment of the spine. The objective of this study was to determine the influence of the parameters of body composition on the prevalence of postural disorders in the sagittal plane. The cross-sectional study was conducted on 152 children of both genders (78 boys), at a mean age of 11 years ± 6 months. In order to evaluate postural disorders, the Formetric 4D System, a tool manufactured by Diers, Schlangenbad, Germany was used. Based on its output data, the following variables were obtained: hyperkyphosis, hyperlordosis, kypholordosis, flatback, and normal alignment of the body in the sagittal plane. The evaluation of body composition parameters was conducted using the InBody 770 device. To determine how body composition influences the postural status of the spinal column, a discriminant analysis was employed. The results showed that approximately 65.8% of children exhibit various types of postural disorders when assessing the alignment of the spine in the sagittal plane. The most prevalent disorder observed was hyperkyphosis, affecting 34.2% of the subjects, followed by kypholordosis at 16.4%. Moreover, the results demonstrated that body composition significantly influences body posture (p = 0.004). An increase in fat mass corresponds to a deviation from normal body posture, whereas an increase in the percentage of skeletal muscle mass and fat-free mass is associated with a reduction in postural abnormalities in the sagittal plane. Considering the results, it is clear that body composition parameters serve as more reliable predictors of the influence on body posture compared to simply calculating the body mass index. Furthermore, it can be concluded that there are consistent patterns of influence by specific body composition parameters, including fat mass, percentage of skeletal muscle, and fat-free mass, on body posture among children from various climates. These results underscore the significance of implementing strength exercises in children, particularly during periods of rapid growth and development, as a means of preventing and correcting postural disorders.