The Asia-Pacific constitutes the fastest growing region in mobile and social media penetration. Yet, the political implications of the technologies are not fully understood. Using probability samples of university students in Taiwan, Hong Kong, and China, this study examines the roles of mobile and social media news in offline and online political participation. Consistent with the O-S-R-O-R model (Orientations–Stimulus–Reasoning–Orientations–Response), which derives from communication and cognitive mediation models explaining the relationship between media use and political participation, all three samples demonstrated indirect relationships between mobile/social media use and political participation through interpersonal political discussion and political efficacy. The study contributes to theory building by demonstrating the external validity of the O-S-R-O-R model across different political systems.