This study examines the relationship between social media use among older adults in South Korea and civic engagement both at the national level (national political interest, political efficacy, and national political participation) and at the local level (local interest, collective efficacy, and local participation). This study was guided by communication infrastructure theory and the social media dependency model. We focused on Kakao Talk, one of the most popular social media in South Korea, for this study. We modified the existing concept of social media dependency to address the dependency relationships of older adults with Kakao Talk. Using interviews with respondents aged 65 years or older (NN = 280), we found that their social media dependency (measured as Kakao Talk dependency) was associated with local interest, collective efficacy, local participation, national political interest, and political efficacy. However, social media dependency was not associated with national political participation. We then compared the difference in effect sizes for interest, efficacy, and participation at the local and national levels. The results showed that the differences in effect sizes between the local and national levels were not significant for interest and efficacy, but the difference in effect sizes was significant for participation.