This study investigates how individuals conduct different modes of political participation via different usage dimensions of social networking sites (SNS) in three Chinese societies, i.e., mainland China, Hong Kong, and Taiwan, respectively. In mainland China, channels for political action are restricted and flow of online information is censored. Hong Kong, on the other hand, is a media-saturated society, but people only have limited political rights. Taiwan is an established democratic society. This study moves away from the past literature on new media and politics, where the uses of SNS were regarded as unidimensional and political actions were disproportionally referred to electoral-related participation. It discerns three modes of participatory behaviors: a) the canonical mode of participation, that is, political actions that aim to influence a government's or institution's decision-making process or making individual or collective political concerns known to the public or officials, b) the contacting/lobbying mode of participation, that is, those behaviors conducted via private contacts, such as contacting and seeking help from personal networks, or lobbying the officials privately, and c) the participation initiated by the ruling party to reinforce legitimacy. Meanwhile, the study distinguishes among four dimensions of SNS uses: a) the informational and instrumental uses; b) the social networking uses, c) the recreational and entertainment uses, and d) the SNS-based political activities. The study proposes that the four dimensions of SNS uses have different impacts on the three modes of political participation. Additionally, the study proposes that the political impacts of use of SNS are conditional on political cynicism, which is defined as a negative perception towards government's trustworthiness and responsiveness. The study further examines whether the patterns of the conditional impact of the use of SNS on political participation are different among the three societies. Comparative surveys using the multistage cluster sampling method were conducted in large and comprehensive universities of Guangzhou, Hong Kong, and Taipei, respectively (total valid N = 965). Results show that the three societies demonstrate significant variances among the three modes of political participation. The four dimensions of use of SNS have significant impacts on political participation. The impacts of the use of SNS are conditioned on political cynicism in mainland China and Hong Kong, whereas the moderation patterns of political cynicism are different. In the authoritarian mainland China, the informational and instrumental uses of SNS helped the political cynics to engage in the canonical mode of participation. Meanwhile, the effects of the social networking uses of SNS on the contacting/lobbying mode of participation were larger for those who had lower levels of political cynicism. In contrast, in Hong Kong, the associations between the social networking uses of SNS and the canonical mode of political participation were stronger among those who reported lower levels of political cynicism. Similarly, the effects of the instrumental uses of SNS on the contacting/lobbying mode of participation were stronger for those who were less cynical to the government. Besides, the study reveals that the positive relationship between the instrumental/information uses of SNS and voting in the 2012 Legislative Council in Hong Kong were stronger among those who had higher level of cynicism towards the government. The study also finds that the use of SNS, regardless of the dimension of usage, did not facilitate the 2012 Presidential Election in Taiwan. The study provides new evidences that individuals' engagement in politics is based on the joint impact of SNS usage and political attitudes. SNS may help individuals or groups express political concerns, but it can be also be used for private benefits or in the interests of the single-ruling party in authoritarian states.