Purpose Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine. Orthoses are the most commonly used treatment material in AIS. However, the physiological and psychological problems that arise due to these orthoses' rigid structures prevent their use by patients. Due to these problems, the authors have developed a posture supporting garment (soft exosuit) design for individuals aged 10-18, with Cobb angles of 25 degrees-40 degrees, which is the most rapidly progressing stage of the disease. Design/methodology/approach Soft exosuit prepared with experimental research method and user-centered design approach. The posture supporting effect is achieved by pattern engineering using fabric, belts, baleens and a gradual zipper system for to increase functionality, ease of use and fit. Findings The first six-month clinical trial in prototype use was carried out with a female patient with a 29 degrees scoliosis Cobb angle and suitable wearing a rigid corset due to AIS. The patient was satisfied with the prototype and its functionality, ease of use, fit and comfort. Cosmetic body deformity due to scoliosis was not observed, and the Cobb angle was decreased by 10.7% at the end of the sixth month. Soft exosuit has been found effective in supporting the posture of individuals who had ongoing spinal growth. Research limitations/implications The most important limitation of this study is that, despite a large number of prototype and prototype studies, trials could not be conducted on a large number of patients with different characteristics due to the COVID-19 pandemic. More experimental studies are needed to generalize the product to large audiences. The first goal is to investigate more patients with different spinal deformities in the future. The second goal is to measure the materials used and the quantitative measurement of body responses with the biomechanics field. It is planned to increase the soft exosuit functionality with smart textiles by adding wearable devices with future research. Practical implications This study is important because it constitutes the basis for future studies on pattern cutting soft materials' positioning. Social implications It is thought that the study will contribute to functional solutions for different spinal deformities. Originality/value It is an entire functional soft garment without an actuator. It is customizable and modular for patients with spinal deformities. It is thought that the study will contribute to functional solutions for spinal deformities.