Purpose: To examine the mediating role of mindfulness in the relationship between passive social media use and irrational procrastination among university students. Methods: An online survey was conducted with 293 university students in City B using a scale measuring passive social media use, irrational procrastination, and mindfulness. Descriptive statistics, regression analysis using SPSS Process v4.2 macros, and bootstrapping analysis were used to analyze the data. Results: The independent variable, passive social media use, was significantly negatively correlated with the mediating variable, mindfulness, and significantly positively correlated with the dependent variable, irrational procrastination. Next, in the relationship between passive social media use and irrational procrastination, mindfulness was found to significantly partially mediate the relationship between the independent and dependent variables. Conclusion: The findings of this study are significant in that they identify the psychological mechanisms at play in the process of passive social media use leading to irrational procrastination among college students. Mindfulness was found to be a mediator of the effects of passive social media use on irrational procrastination, suggesting that interventions aimed at increasing users’ levels of mindfulness may be effective in preventing passive social media use from adversely affecting important academic aspects of college students’ lives.