Social media increases opportunities to glimpse celebrities’ glamorous lifestyles and to interact with celebrities. This study examines how the use of social networking sites (SNSs) for celebrity-related information and interactions influences users’ life satisfaction. Data analysis demonstrates that celebrity-related SNS activities decrease users’ life satisfaction by increasing relative deprivation through comparison with celebrities. However, the comparison also leads to system justification, serving a palliative function to cope with the potentially negative consequences of such comparisons, which in turn increases life satisfaction. Interestingly, materialism moderates the relationship such that the effects of comparison with celebrities on system justification are observed only among SNS users who hold high materialism values. Also, the direct positive effects of celebrity-related SNS use on life satisfaction are stronger for those with high materialistic values than for those with low materialistic values. The multifaceted functions of celebrity-related SNS activities for life satisfaction are discussed.