<p>This meta-analysis aims to synthesize original studies on the relationship between social exclusion and depressive symptoms and to analyze factors that may moderate this relationship. We searched eight electronic databases (Web of Science Core Collection, Medline, EBSCO-ERIC, PsycINFO, PsycArticles, Elsevier SD, ProQuest Dissertations and Theses, and China National Knowledge Infrastructure Database) and screened published studies up to October 18, 2025. A total of 91 effect sizes were extracted from 77 empirical studies (42 studies were rated as moderate quality and 35 as high quality), involving 74,436 participants, with the correlation coefficient <i>r</i> used for calculation. Given the high heterogeneity observed across studies (<i>I</i>² = 95.69%), a random-effects model was adopted. The results showed that there was a significant positive correlation between social exclusion and depressive symptoms in children and adolescents, with a large effect size (<i>r</i> = 0.40, 95% <i>CI</i> [0.37, 0.43]). Further analysis supports a causal model in which social exclusion acts as a precursor to depressive symptoms (<i>β</i> = 0.09, <i>p</i> = 0.03), rather than the reverse. In addition, this relationship was moderated by gender, age, measurement tools, and sampling years, but not by the cultural background or types of social exclusion. Specifically, the relationship between social exclusion and depression was stronger in females and senior high school students. In summary, this study clarifies the strength of the association between social exclusion and depressive symptoms in children and adolescents and identifies key moderating factors, providing important insights for future research and intervention efforts. Furthermore, by providing open access to the dataset and literature, this study serves as a valuable resource for future cross-cultural research.</p>