The fashion industry plays a significant role in global environmental degradation and social inequality due to its unsustainable consumption patterns. Therefore, understanding the barriers hindering the adoption of sustainable consumption practices in this industry is crucial for promoting positive change. This research aims to identify and analyze the barriers to sustainable consumption in the Vietnamese fashion industry using a two-stage data-driven model-based Grey theory system (Grey Delphi- Grey DEMATEL). To achieve this objective, a comprehensive literature review was conducted to identify the key barriers affecting sustainable consumption in the fashion industry. The critical barriers include social and cultural perspective, pricing and affordability, policy and education, perception and image, and supply chain and industry practices by developing a structured questionnaire that was distributed to 16 valid industry experts and professionals in Vietnam. The Grey Delphi technique is applied to validate 30 critical barriers to sustainable consumption in the Vietnamese fashion industry. The Grey DEMATEL model is employed to determine the causal relationships among selected barriers, considering both the direct and indirect influences. Additionally, the Grey theory system with Grey numbers was integrated into the model to address uncertainties and vagueness associated with the data. By employing the proposed model, the research provides a comprehensive understanding of the complex relationships between the identified factors and their impact on sustainable consumption. The outcomes of this research will enable industry stakeholders, policymakers, and researchers to develop targeted strategies and interventions to overcome these barriers and promote sustainable practices in the Vietnamese fashion industry. Keywords: Sustainable consumption, barriers, fashion industry, Vietnamese, DEMATEL, Grey theory system.