Nonsuicidal self-injury (NSSI) is prevalent and concerning among adolescents and adults. Although prior meta-analytic work has considered the efficacy of individual psychotherapy for reducing NSSI, the efficacy of group psychotherapy remains unclear. We conducted a systematic meta-analysis of group psychotherapy studies with NSSI measures. We identified a total of eight studies, including published articles (n = 6) or dissertations (n = 2) with 10 total effect sizes for group interventions. Overall, random-effects meta-analysis suggests that group psychotherapies have a significant small effect on NSSI. However, when corrected for publication bias, the effect is no longer significant. This meta-analysis cautiously suggests that group psychotherapies, which are cost-effective and efficient, hold promise for attenuating NSSI. The field would benefit from further study and treatment refinement, including consideration of what works for whom.