OBJECTIVES: About one in four mothers will experience depression and anxiety during pregnancy and within their first year following childbirth. The meta-analysis aggregated the findings of randomized controlled trials (RCTs) evaluating the immediate post-intervention and maintenance effects of MBI on perinatal depression and anxiety. METHODS: A systematic search was conducted in PubMed, PsycINFO, Medline, Scopus, and Web of Science for English-language journal articles from the first available date until Oct 27th, 2022. RESULTS: Twenty-five published RCTs were identified and reviewed, with a total of 2495 perinatal women. MBI was superior to controls for clinical and subthreshold perinatal depression and anxiety. The benefit for depression reduction was stable over time and sustained to the postpartum period, but the maintenance effect on perinatal anxiety was less conclusive. Moreover, MBI's post-intervention effects on depression and anxiety were moderated by perinatal women's symptom severity. The post intervention effects were significantly greater among women in Low- and Middle-Income countries, where perinatal mental health care is less available and accessible. Greater improvement in mindfulness was also associated with a significantly larger post-intervention effect on perinatal depression. CONCLUSIONS: This meta-analysis suggests that MBIs may complement and extend the available range of effective interventions for clinical and subthreshold perinatal depression and anxiety.