This study examined the impact of media use on political engagement among South Korean voters. The two major strengths of the current study were the examination of multiple dimensions of media use and citizen communication, and the consideration of mediating variables. Multigroup structural equation modelling was used to examine the direct and indirect effects of media use on political engagement via mediator online citizen communication. The present study used data from the 19th General Election Survey in Korea conducted by the Korean Social Data Center. A nationally representative sample of 829 Korean voters (age range: 21–59) was included for analysis. Results indicated: (1) for those in the 20–30 year age group, political efficacy positively predicted online media use and this, in turn, was related to political engagement via mediator online citizen communication; and (2) for those in the 40–50 year age group, political efficacy positively predicted both offline and online media use, with online media use affecting political engagement directly.