The purpose of this study is to develop customized suit designs incorporating flower and bird painting patterns from Korean folk painting and to propose differentiation strategies for customized fashion design in Korea. The research was conducted in three stages. First, concepts and types of customization were examined through theoretical analysis, identifying the characteristics of customized design. Second, flower and bird painting patterns found in Korean folk painting were classified according to their symbolic meanings and developed into digital patterns. Third, flower and bird painting patterns from Korean folk painting were utilized in the suit designs following the principles of customized design. The results are as follows. Customizations were classified into three types: simple combination, selective adjustment, and creative assembly. The characteristics of customized design were identified as customer participation and product modularity. The symbolic meanings of the flower and bird motifs were categorized into six themes: happiness, wealth, longevity, fertility, love, and protection against evil. The resulting digitally developed patterns sought to integrate traditional cultural elements into customized fashion design. The final suit designs demonstrated hyper-individuation through modular assembly, enabling both customer participation design and product modularity. Detachable elements that modularize the jacket structure enhanced customizability while promoting sustainable and eco-conscious design practices.