The aim of our study was to investigate the effects of a 24-week-long training program on changes in static body posture, as well as the characteristics of anterior shoulder pain in youth swimmers, and the relationship between changes in whole-body posture and the frequency and intensity of anterior shoulder pain. Competitive young swimmers (n = 54, 13.9 ± 1.79 years) were divided into experimental group and control group and both groups performed their usual swimming training. In addition, the experimental group performed a 24-week-long whole-body posture correction program. Before and after the implemented training, whole-body posture was analyzed using the PostureScreen (version 13.7) mobile application, and subjective intensity of pain was determined using the swimmer’s functional pain scale. Significant changes were found between the two groups in numerous measured postural parameters. A significant reduction in the prevalence of shoulder pain and score of the pain scale was observed after the posture correction program in the experimental group. Our results may imply that more optimal biomechanical conditions may indirectly reduce the incidence of swimmer’s shoulder in terms of prevention. Analysis and monitoring of body posture of swimmers using an on-field mobile application continuously, and the application of preventive training programs, may help to avoid developing injuries.