Objectives: We conducted a meta-analysis of randomized controlled trials to investigate the therapeutic effects of mindfulnessbased interventions on depressive symptoms in patients with major depressive disorder. Methods: In February 2021, we searched Embase, MEDLINE, Cochrane Library, PsycINFO, CINAHL, and AMED. Under the guidance of the corresponding author, two evaluators independently reviewed and selected articles based on predetermined selection criteria. Results: Based on the selection criteria, we systematically screened and included a total of 12 randomized controlled trials comprising 720 cases for the final analysis. Utilizing a random-effects model for data analysis, we determined the Hedges’ g value to be 0.787, indicating a medium-sized effect according to Cohen’s interpretation. The 95% confidence interval for the effect size ranged from 0.414 to 1.160 (p-value < 0.0001). Conclusions This study reveals the potential effectiveness of mindfulness-based interventions in treating depressive symptoms among patients with major depressive disorder.