Objectives <p>This study examined how mindfulness relates to sustainable consumer behavior (SCB) through two psychological pathways, minimalism and self-transcendence, and whether this process is conditioned by collectivism. Prior research reporting mixed findings suggests the need to clarify indirect mechanisms and cultural boundary conditions in the mindfulness-sustainability link.</p> Method <p>A cross-sectional online survey was conducted with 468 Vietnamese consumers. Measures included mindfulness, minimalism, self-transcendence values, collectivism, and SCB. Partial least squares structural equation modeling (PLS-SEM) was used to evaluate the structural model, including multiple mediation and moderation pathways. Predictive relevance was assessed using PLSpredict.</p> Results <p>Mindfulness showed a modest direct association with SCB; however, stronger effects emerged through indirect pathways. Mindfulness predicted higher levels of minimalism and self-transcendence, which independently and sequentially related to more sustainable consumption. Collectivism significantly strengthened the relationship between mindfulness and SCB but did not significantly moderate the mediation pathways. The model demonstrated explanatory adequacy and positive predictive relevance.</p> Conclusions <p>This study provided preliminary evidence clarifying the role of mindfulness in sustainable consumption within a collectivist cultural context. Additionally, the current study also offered initial support for minimalism and self-transcendence as potential mechanisms linking mindfulness to sustainable consumer behavior, and for collectivism as a contextual factor influencing this relationship.</p>