<p>Sustainable tourism has become an urgent priority, especially as global travel contributes significantly to environmental degradation. Despite this, limited attention has been paid to the role of social and personal norms in shaping responsible tourist behaviour, particularly in the context of misinformation spread through social media. This study examines how injunctive and descriptive norms influence sustainable tourism behaviour, with personal norms acting as mediators and social media rumors as moderators. Data were collected from 780 tourists across five major destinations in Northern Pakistan using a structured questionnaire. The study employed Partial Least Squares Structural Equation Modeling (PLS-SEM) to test the hypothesised relationships based on the normative conduct theory and the elaboration likelihood model. The findings indicate that injunctive and descriptive norms significantly predict personal norms, which in turn influence tourists’ intentions to revisit destinations and engage in positive word-of-mouth. Personal norms also significantly mediate the effect of social norms on sustainable behaviours. Notably, social media rumors moderate these relationships, amplifying or diminishing the influence of norms depending on their nature. The study offers robust theoretical and practical contributions for academicians and tourism stakeholders.</p>