•The present study examined the role of social support seeking through Facebook (SSS through FB).•Daily stress positively predicted adolescents’ SSS through FB.•SSS through FB directly increased adolescents’ depressed mood.•SSS through FB indirectly decreased adolescents’ depressed mood.•This harmful impact of SSS exclusively occurs in a social networking site context. This study examined relationships among daily stress (i.e., school- and family-related stress), social support seeking through Facebook, perceived social support through Facebook, and depressed mood among adolescents (N=910). Structural equation modeling showed that daily stress positively predicted adolescents’ seeking of social support through Facebook. In addition, when social support was sought on Facebook and subsequently perceived, social support seeking through Facebook decreased adolescents’ depressed mood. However, when social support was sought on Facebook, but not perceived, social support seeking through Facebook increased adolescents’ depressed mood. When comparing these relationships with similar relationships in a traditional social support context, results showed that the exacerbating impact of social support seeking on depressed mood exclusively transpires in a social networking site context. The discussion focuses on the understanding and explanation of these findings, and directions for future research.