This study examined the mediating role of ostracism in the relationship between adolescents' attachment styles and depression levels. The sample of this study consists of 621 adolescents (66.8% (n = 415) female and 33.2% (n = 206) male) living in one of the developed cities in Turkey. The results showed that ostracism partially mediates the relationship between secure, avoidant, and anxious-ambivalent attachment styles and depression. Based on the results of the study, we confirmed that ostracism partially mediates the relationship between secure attachment and depression. Secure attachment predicted ostracism and depression negatively; we found that ostracism predicted depression positively. Secondly, we found that avoidant attachment predicted depression and ostracism positively, and ostracism played a mediating role in this relationship. Finally, we concluded that anxious-ambivalent attachment positively explains ostracism and depression and that ostracism plays a mediating role in this relationship.