The global unsustainable production and consumption patterns in the fashion and textile industry are a prevailing problem. With the rising trend of European brands reshoring their textile manufacturing and upcoming circular economy frameworks from the EU, the Turkish textile industry may face pressures to transform towards circularity in order to remain competitive. To address the research gap concerning prevalent challenges to implement circularity principles in the critical stage of product design, the purpose of this thesis is to explore the barriers to adopting circular product design in the Turkish textile sector from a manufacturers perspective. This study was conducted in Istanbul with eleven textile and apparel manufacturers of different kinds. To reach a nuanced understanding of each perspective, a qualitative research methodology, through semi-structured interviews with factory managers, was used. The empirical findings of barriers are categorised as internal (financial, responsibility, knowledge) and external (country- and industry-specific). Major internal barriers include prioritising profits over circularity, prioritising customer demand over circular design, and unfamiliarity with key concepts. Country-specific external barriers include lack of competent personnel in Turkey and harsh taxation policies. Industry-level barriers include insufficient resources, limited control over fast-fashion demands, and lack of innovative technologies. This thesis contributes to an increased understanding of the scarcely researched topic and enables practitioners to develop efficient policies and business strategies to ease sustainable business development. Future research is suggested to explore drivers and strategies to apply circular product design within the Turkish textile industry. Additionally, further research can be conducted where this study is replicated but from the perspective of brand retailers with procurement operations in Turkey.