Sustainable tourism is increasingly recognized as a crucial development orientation in the context of globalization and escalating environmental crises. Generation Z, characterized by progressive thinking and high digital proficiency, is expected to be a driving force in promoting responsible travel behaviors. However, in Ho Chi Minh City, a significant gap persists between sustainable awareness and actual behavior within this demographic group. This study employs a qualitative approach, utilizing semi-structured in-depth interviews with five individuals from Generation Z to identify key barriers to the implementation of sustainable tourism practices. The analysis reveals four main categories of constraints: psychological (e.g., diffusion of responsibility, present bias), institutional (e.g., lack of incentive mechanisms, non-transparent information), market-based (e.g., high costs, limited options), and technological (e.g., limitations of digital platforms). These barriers not only undermine individual motivation but also reflect structural shortcomings in supporting sustainable behavior. The study contributes to a deeper understanding of green consumption behavior in urban contexts and provides implications for policy development and communication strategies tailored to younger generations.