Denim originated as a garment material that prioritized durability and functionality. Positioned as a staple of working-class attire, it gradually moved beyond a purely functional textile, becoming a powerful symbol of youth culture, individual expression, and global fashion dynamics. This trajectory reveals how denim has been repeatedly reinterpreted across different social, cultural, and economic contexts. Accordingly, this study undertakes a design-led case study of Mavi’s youth-oriented denim line. Adopting a multi-faceted lens, the paper considers both denim’s evolution from past to present and how it is currently positioned within the fashion industry under the rubric of sustainability. In doing so, it highlights the conjunction of material durability and cultural meaning with contemporary expectations for ethical production and reduced environmental impact. Findings map three actionable design levers - (i) materials (organic/recycled and cellulosic blends), (ii) processes (low-water/laser finishing), and (iii) use-phase longevity (achieved through fit engineering for comfort/durability and timeless, minimalist styling) - that align premium aesthetic cues with lower environmental impact and support the paper’s conclusions regarding product-level sustainability. The primary contribution of this research is a transparent, reproducible case protocol and an evidence-based discussion linking youth preferences to concrete design and production choices in sustainable denim fashion.