Postural alterations that are associated with the orientation of the head, shoulders, scapula, and pelvis in the three basic planes of the human anatomy are commonly found in adolescents with scoliosis. Yet there is a lack of functional garments in the market specifically designed for postural control to address early scoliosis in adolescents. The purpose of this study is to determine the effectiveness of a functional garment for girls aged 10–13 who have the early stages of scoliosis. The effects of this functional garment on postural changes are investigated in this study. Nine subjects have been recruited to take part in the study. A wear trial has been undertaken for 6 months to evaluate the effectiveness and practical use of the posture correction girdle by 3D motion capturing and 3D body scanning. After carrying out the 3D motion capturing, significant postural improvements are mainly found in the acromion and pelvis as observed from the frontal plane during standing, the back angle as observed from the sagittal plane during sitting, as well as control of the maximum range of anterior and lateral bending. After implementing the 3D body scanning, it is found that there is no significant change in the rotation angle in the horizontal plane due to a large standard deviation. The design of the functional garment is found to better control the acromion. The effectiveness of the girdle on postural changes could be affected by compliance, growth and curve type.