In response to the evolving e-commerce landscape, the study investigates changing patterns of social networking site (SNS) usage during a pandemic. Grounded in the interaction of the person-affect-cognition-execution model for addictive behaviors and the appraisal and coping theory, it explores the depth and extent of SNS usage. Specifically, the study examines the moderated mediating effect of perceived stress (PS) and fear of missing out, with risk mitigation behavior as a moderator. With data from a nationwide survey in Korea with 760 responses, results show that risk mitigation behavior moderates the relationship between infection threat and PS, while PS and fear of missing out mediate the effect of infection threat on SNS usage. The moderated mediation of PS was significant, shedding light on the complex psychological mechanisms that drive SNS behavior during global crises. The findings deepen understanding of how stress and coping strategies shape SNS engagement in response to crisis.