In the contemporary landscape, where sustainability becomes increasingly urgent, circular design emerges as a revolutionary approach, integrating the principles of the circular economy and systems thinking. This methodology not only rethinks how materials, design, and business models are interconnected but also promotes a completely new perspective on product creation. By fostering creativity and empowering designers to develop more resilient and prosperous solutions, circular design focuses on eliminating waste and pollution, ensuring the continuous circulation of products and materials, and regenerating nature. One of the greatest challenges in recycling apparel products lies in the complexity of material separation. This applies both at the macro level, considering fastenings and accessories, and at the micro level, examining the composition of fabrics. Within this context, monomaterial design emerges as a crucial strategy to facilitate the disassembly and reuse of post-consumer apparel products, making the end-of-life recycling process more viable. This research delves into monomaterial fashion design as a vital circular strategy for end-of-life recycling of products. Through the presentation of the Retex Project as a case study, we explore the possibilities and benefits of monomaterial design, highlighting its significant contribution to sustainability in the fashion industry.