In the risk society, the development of technology is not only a measure of modernity but also an important factor causing uncertainties. With the popularity of social media, the new communication technology has greatly changed the landscape of risk communication, making relationship between media use and cognitive risk more complicated. To investigate the potential impacts of the online environment on public reactions to risk, the current study conducted a survey on nuclear radiation risk among social media users living near nuclear power stations. A social-cognitive model of risk information seeking was developed, which demonstrated the signifcant motivating role of social media information quality on knowledge, risk perception, and information seeking self-effcacy—three direct predictors of information seeking behavior. Findings of this study suggested the online environment’s potential to increase public awareness of risk and promote proactive learning about risk. These fndings have practical implications for public-oriented risk communication.