ABSTRACT Social media fatigue negatively affects users' cognitive, emotional, and behavioral faculties. Therefore, the identification of risk factors associated with this phenomenon is essential for the development of preventative measures against social media fatigue. This study aimed to explore the relationship between fear of missing out and social media fatigue, the mediating role of information overload and perceived stress, and the moderating role of dispositional mindfulness. Adopting a longitudinal cluster sampling design, this study assessed college students using several psychometric instruments: Fear of missing out scale, information overload scale, Chinese perceived stress scale, social media fatigue scale, and mindfulness attention awareness scale. Data from 743 college students, collected and matched across three‐time points, were analyzed to test the mediation and moderation effects. Findings from the study indicated that the independent and chain mediating effects of information overload and perceived stress were significant. Moreover, the negative moderating influences of dispositional mindfulness were also found to be significant. The results suggest that fear of missing out influences social media fatigue through two parallel pathways—information overload and perceived stress—and through a serial pathway involving both variables. Dispositional mindfulness can mitigate the impact of fear of missing out on information overload or perceived stress, as well as alleviate the mediating role of information overload and perceived stress. These findings provide valuable insights into social media fatigue and have significant implications for its prevention and intervention.