<p>Despite the growing body of literature on 4D printing and sustainable manufacturing, existing studies largely focus on technological advancements, material innovations, or isolated barrier identification without systematically analysing the interdependencies among these barriers. Furthermore, prior research has rarely incorporated uncertainty-aware decision-making frameworks capable of capturing expert hesitation in evaluating complex, emerging technologies. In addition, the absence of a structured sustainability-oriented causal framework limits the ability of policymakers and practitioners to prioritise interventions effectively. To address these gaps, this study integrates hesitant fuzzy set theory with the DEMATEL approach to model causal relationships among sustainability barriers under uncertainty. Unlike prior studies, this research provides a quantified cause–effect structure, identifies key driving barriers, and develops sustainability indicators that offer actionable insights for both academia and industrial practice. Thus, the study contributes to advancing methodological rigor and practical relevance in sustainable manufacturing research.</p>