Firms frequently use message prompts to influence consumer decision-making and behavior. However, research on the boundary conditions and mechanisms driving the effects of these prompts remains limited. The present research investigates how perceived self-control and dialectical thinking influence the effectiveness of message sidedness (one-sided vs. two-sided messages) on sustainable behavioral intentions. Across the experiments, we found that two-sided message prompts were more effective for consumers with high self-control. The interaction between message sidedness and self-control was serially mediated by perceived trust towards the message prompts and the platform. Additionally, dialectical thinking enhanced consumers' perceived trust in two-sided message prompts, further boosting sustainable behavioral intentions. These findings contribute to a better understanding of prompt effectiveness and offer practical guidance for firms, platforms, and policymakers on promoting sustainable consumption more effectively.