Many countries adopted lockdown measures to curb the spread of the outbreak in 2020, while information about COVID-19 has dominated various media outlets, which has led to information overload for people. However, previous research has mainly focused on cancer information overload and the corresponding consequence, and failed to examine its adverse effects in the context of major public health events. Based on the Frustrate Aggression Theory and the Scapegoat Theory, the present study established a moderated mediation model to investigate the emotional and behavioral outcomes of COVID-19 information overload. The mediating role of depression/anxiety in the association between COVID-19 information overload and cyber aggression, as well as the moderating role of Confucian responsibility thinking, were tested. This model was examined with 1005 Chinese people (mean age = 26.91 years, = 9.94) during the COVID-19 outbreak. Mediation analyses revealed that COVID-19 information overload was positively related to cyber aggression, depression, and anxiety, parallelly and partially mediated this relationship. Moderated mediation analyses further indicated that Confucian responsibility thinking not only moderated the direct link between COVID-19 information overload and cyber aggression, with the effect being significant only for people with a low level of Confucian responsibility thinking, but also moderated the relationship between COVID-19 information overload and depression/anxiety respectively, with the associations being much more potent for individuals with low levels of Confucian responsibility thinking. These findings have the potential to inform the development of prevention and intervention programs designed to reduce the negative emotions and cyber aggression associated with information overload in public health events.