Background: Peer relationships become the central arena in which attachment processes are likely to play out during adolescence and beyond, and contribute to various aspects of psychosocial adjustment. Objective: Given the relevance of peer connections and the growing literature examining them, the purpose of this article was to review, through a meta-analytic approach, the evidence of the links of youth close peer relationships with internalizing problems within the theoretical framework of attachment. Methods: Journal articles were searched in PsycINFO, PsycARTICLES, ERIC, Web of Science, and Scopus electronic databases; in journals most likely to publish papers on peer attachment; and in reference lists of selected papers. Thirty-six studies were included in the meta-analysis. Results: The findings showed significant moderate correlations between peer attachment and anxiety, depression, and internalizing problems. Additional analyses indicated that the dimensions of attachment more strongly related to depression were alienation and trust, whereas peer communication was weakly related to depression. Findings were characterized by significant heterogeneity across studies that was partially explained by the results of moderator analyses. Conclusions: This study suggests that secure peer attachment might make young people less vulnerable to symptoms of depression and anxiety. Insecure peer attachment, on the other hand, is associated with an increased likelihood of experiencing internalizing symptomatology. Additionally, this study shows the moderating effect of gender suggesting that peer attachment is more strongly related to depressive symptoms in adolescent girls.